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Why do people cheat? Dateline explores

Infidelity breaks hearts and raises questions, often perplexing ones: Why does someone cheat? Dateline explores whether the reasons are different for men and women, and if it's possible to affair-proof your marriage.
/ Source: Dateline NBC

Go ahead: Set the date.  Order the gown, the flowers, the photographer. Then, when you've said your I-dos and promised to be faithful forever, build your dream house, and your family. But keep this in mind.  No matter how carefully you've laid out your future together, chances are you never made plans for this…

Ed Hooke: I would sleep with this woman and come home, and lay down and put my arm around my wife.  And sleep with my wife.

Angela Sanders: I was literally shaking and-- and I knew-- I-- I strongly suspected what he was gonna tell me.  And-- and I was scared to death.

A new look at one of the oldest sins in the good book: Infidelity.

Hoda Kotb: Men cheat because they want sex.

Gary Newman: Absolutely not.

How can you tell when a spouse is about to go AWOL?

Joe Ussery: She'd be wearing something a little more provocative.  And still no interaction with me.

We know infidelity - lust and love - can all feel intoxicating. It's called dopamine.  And that is what is released and exists in very high levels during new lust.  And it's very addictive. 

But is that what makes us falter?  Or is it something else?  In the lab, science may be closer to finding out why some stay true and others drift.  And a new lie detector may spell doom for every cheating heart.

Hoda Kotb: Are you confident that when you take that MRI exam that you will pass that?

Ed Hooke: Yes.

When all is said and done, is a spouse's betrayal the worst that can happen to a marriage?

Sarah Symonds: The mistress is the one that's sitting at home lonely in emotional trauma.  But the husband's actually going home a happier, brighter man.

Infidelity now.  We'll go to the frontlines. Meet the betrayers -- and the betrayed.

For a long time, Marie Hooke of Connecticut thought marriage was fine -- for other people.  She'd been down that aisle before, only to have it end in heartbreak and divorce.  And then, as a single mother of three, she met Ed.

Ed Hooke: I thought she was beautiful.

So Marie gave into love, and hope, again. The two married in 1990.  For much of their marriage, Marie tried to shower her man with affection.

Ed Hooke: She would give me little notes in my lunch when she was making my lunch for me.

Hoda Kotb: You did?

Ed Hooke: She was--

Marie Hooke: What-- special ingredients to make any flavor ice cream that you could ever want.

Ed Hooke: Yeah.

And for the first four years of marriage, their sex life was healthy.  But then Marie admits the romance lost some of its bloom.  Injuries from a car accident and, later, menopause, sidelined her in the bedroom.   She thought Ed understood.

And then it was New Year's 2007.  Ed and Marie had been married more than 16 years.  One of Marie's daughters showed her a card she'd found: a love note written to Ed.  Trouble was, it wasn't from Marie.

Marie Hooke: It was one of those just between us kind of romantic little cards that said “soulmate” and you know, the beating of your heart, and I know how much you love me, when your arms are around me and it was signed by the woman, "Love," the woman's name.

Of course, Marie went straight to Ed.

Hoda Kotb: Okay, so did you feel like, "Oh my God, I'm busted."

Ed Hooke: Not yet, no I didn't.  I felt I could talk my way out of this.

He told her the woman was a coworker with an inappropriate crush on him.  Marie wanted to believe him, but insisted they go into couple's counseling.  Still, Marie's curiosity about that coworker grew.

Marie Hooke: So I decided that I was going to go meet her, to find out if in fact, what I'd been told was true.

She went into detective mode, figuring out when the woman arrived at work.  In February 2007, a month after reading that love note... Marie surprised its author outside her office.

Marie Hooke: I just said, "Listen, I don't-- I'm not here to confront you. It's just that, you know, I have some questions...

That day, over a cup of joe, the other woman spilled the beans about Ed, about her affair with Marie's husband.  That day, Ed came home to an empty house- and a letter from his wife.  Ed realized Marie was leaving him.

Ed Hooke: I started crying.  I thought, the jig is up, pretty much. 

Eventually, Marie did come home after Ed promised to stay in counseling, and leave the other woman for good.  He even confessed to another indiscretion: a few kisses shared with a second coworker.  Nothing more, he swore.

Marie Hooke: He was willing to do all the work necessary to repair-- repair our marriage, to recommit. 

Hoda Kotb: And could you look into the eyes that lied to you and believe him?

Marie Hooke: Then, yes, because I felt that he was confessing the truth.  

Things had been going so well in therapy that she and Ed decided to renew their wedding vows in a full church service.  Family and friends were shocked.  After all, it had only been a few months since Marie had learned of Ed's infidelity.

Hoda Kotb: So you know that there are women who are going to be listening to you and saying, he already cheated twice.  Like, how many times do we have to beat this woman over the head? 

Marie Hooke: Right, right.

Hoda Kotb: "What is wrong with her?" And your answer is--

Marie Hooke: Because when going to a therapist and they give you hope that if you follow these rules, you can rebuild your marriage.

Or was it wishful thinking?  Over the next year, the doubts resumed when Ed gave conflicting stories about his infidelity.

Hoda Kotb: Okay, so in counseling, you were tripping.  Did you notice that you were making mistakes?

Ed Hooke: No, I didn't. 

But Marie did. She went digging for clues, and found them hidden in a phone bill. The same number over and over again.  Marie dialed it and a woman picked up.  Only it wasn't the old mistress, or the other woman Ed said he had innocently smooched.  This was yet another “other woman.”

Marie Hooke: So Ed came home from work.  And I had her on speakerphone, and I said, "Hi, Ed.  I have so-and-so on the phone, and she's telling me a little story about the year 2002."

Ed Hooke: I totally denied everything.  I said to the other woman, "Why are you doing this to me?"

Hoda Kotb: Can I tell you something?  I wouldn't believe one thing he ever told me, from that day.

In fact, Marie didn't believe Ed. Woman number three revealed something else:  She'd slept with Ed, and so had that woman, the one Ed said he'd only smooched.  Eventually, Ed admitted them all: Mistresses one, two, three.  And then he confessed, there was still someone else.

Marie Hooke: Now we got four.

Hoda Kotb: Four.

Ed Hooke: Four.

Marie Hooke: Yeah.

Hoda Kotb: Are-- is that all there is?

Ed Hooke: Yes.

Ed now says his first affair began just six years into his marriage with Marie. 

Ed Hooke: I internalized it as, "She doesn't love me."

Ed said he just wanted more attention and affection.

Ed Hooke: Most of the time was after work, we'd go to a parking lot and talk and kiss and hold each other and comfort each other.  And I only slept with her one time.  That is not a lie.

But how do you know when a cheater is telling the truth?  As we'll see later, Marie has a crucial question to answer: Will she ever be able to trust her husband again?

Angela sanders of Austin, Texas never thought it could happen in her marriage.

Angela Sanders: I thought we were bulletproof.  I was rock solid in that belief.

Hoda Kotb: And same with you, Marshall?  You felt that--

Marshall Sanders: Absolutely.

Angela -- an online project consultant -- and Marshall -- a high school basketball coach -- got engaged in 1995. They were knee-deep in love.  And they wanted an island wedding ceremony, something romantic -- and memorable -- on the beach.  As it turned out, they got memorable -- but no marriage.

Marshall Sanders: As you can see it's raining cats and dogs. There's a hurricane going on right now.

The day before the ceremony - on the Carribean island of St. Thomas - Hurricane Marilyn came barreling along, busting up the best-laid plans.

Angela Sanders: We're still not married.  We had to cancel the wedding, and to be announced when we're gonna re-schedule after the storm.

Marshall Sanders: Because of the hurricane, not because of us.

Angela Sanders: Yeah.

The Sanders rode out the storm in a beachfront condo, their dream of a romantic ceremony in shreds.  When they made it home to Austin -- to get married there -- family and friends told them the hurricane was an omen.

Angela Sanders: They said, "This is a-- you know, a sign that maybe gettin' married's not such a great idea, or you guys are gonna be together forever."

Marshall Sanders: Yeah, you can--

Angela Sanders: One or the other.

Marshall Sanders: --you can weather any storm.

Hoda Kotb: Weather any storm.

And that's how the Sanders chose to see it -- they figured they were storm-proof. After all they'd already resolved their differences on one big issue: sex.   For Marshall, it was all-important. And Angela learned that early on.

Angela Sanders: When we got together, it was a party.  You know, "woo-hoo," you know.  (laughter) But when we lived together and it became a day after day, and I was, "Woo, you're gonna kill me," right.  (laughs)

And I said, "Honey, you have to understand that bein' physical, you know, is not an indicator of how much I love you." 

He says he listened. And Angela thought he accepted that.  But did he really?

Marshall Sanders: I kinda grew up equating, you know, my sexual conquests and activity with-- success, with, you know, with how much a person cared for me.  And--

Hoda Kotb: So, you meant the more sex Angela had with you, the more she loved you.

Marshall Sanders: Exactly.  Exactly. 

As the years passed, and their family grew to include two daughters, they admit that distance crept into their relationship. Angela remembers Marshall not returning phone calls promptly ... Spending more time away from home.

Then -- in summer, 2005 -- a red flag.   Angela saw an odd text message on Marshall's phone.

Angela Sanders: The text said something like, "I miss you.  Call me," something like that. 

But she let it go.  Then, a few weeks later... Another red flag.

She was at home paying bills. On the computer, a drop-down menu of previous phone numbers appeared - and there was one she didn't recognize.

Angela Sanders: For a split-second I thought I wasn't going to pursue it, but just-- it's like a little voice that said, "No, whose number is that? Should I call it?  Do I want to be that girl, you know, to call the number?”

She decided she was -- finally -- ready to be that girl. She dialed that number.

Angela Sanders: It seemed like it rang forever. And I was just about to hang the phone up when the voice mail picked up.  And it was a female's voice.

She called Marshall and arranged to meet him -- without revealing why.  She wanted to see his eyes when she confronted him.

Angela Sanders: I tried to act as normally as I could, but I was shaking.

Marshall Sanders: She tried to make it seem like it was just a normal, you know, kinda "we need to talk."  And we've had a lot of those.

They met at a restaurant.  He got a drink. Then she hit him with it.

I said, "Who is so-and-so?  And is she the reason that we're done?"  And, you know, he looked at me.  He looked at me and he put his head down and he put his head back up.  And that-- that told me.

Hoda Kotb: You knew.  You knew.

Marshall Sanders: My heart just dropped, you know. And, you know, I-- I started to think, you know, just how much does she know?

Hoda Kotb: You're gonna try to minimize the damage.

Marshall Sanders: No question.  I-- at first, you know, I was gonna try to see if I could lie my way through it.

But his wife wasn't going to stick around for his performance.

Angela Sanders: I just got up and I ran out of the restaurant and-- he ran after me, and I just told him to-- leave me alone, you know, "Get away from me." I just told him-- I said, "You've-- you've broken everything,"

In those first stomach-churning moments, Marshall says he knew he was headed for a divorce .... All because of a four-month fling with a college senior he met during an out-of-town trip.

Marshall Sanders: I-- I approached her.  Yeah.

Hoda Kotb: And you went up to her, and just started chatting?

Marshall Sanders: Yeah.  Led to the exchange of number, and stuff like that

Hoda Kotb: How did it go from exchanging numbers to an affair?

Marshall Sanders: Really-- kinda easily.

At the time, Marshall says he justified the affair to himself like this:  He and Angela weren't as intimate -- as often. 

Hoda Kotb: How much of it was the-- was the excitement of the secrecy?  //how much of it was that?

Marshall Sanders: I-- I think that's a huge part of it.  I think that's a huge trap that we fall into, is that, you know, it-- it can be more titillating.  It can be more glossy, and more glamorous. "I'm gonna go, you know, fly to meet someone, and gonna have a sexual rendezvous. Or, I can go home and-- and help Angie clean up the floor I think that's a trap that I fell into, and a lot of men fall into.

But now it looked like he'd destroyed his marriage. Certainly that's how his wife saw it in those early days.

Angela Sanders: I didn't see how I was gonna be able to get past that.

It's easy to see why.  Even easier to blame her anguish on a man's failings.  But when it comes to infidelity and cheating husbands, maybe the fault lines are not so clear cut after all...

It's time to find out if your man is cheating.  Can you really handle the truth?  Even if you could, would you know how to uncover it?  What's the first step?  A trip to a psychologist's chair? Or maybe you could get the scoop from Sarah.

Sarah Symonds: --I always say that I think men are born to cheat.  It depends what type of relationship they--

Hoda Kotb: I'm so depressed (laugh).  Oh, God.

Sarah Symonds: Welcome to my world.

That “world” would be the one Sarah Symonds used to live in.  The one where mistresses lurk in the shadows like secret agents... Where married men are desperate for sex... And wives have let things go too far...

Sarah Symonds: So many wives let things slip.  Mistresses don't.  When a guy goes to his, mistress, guaranteed she's going to open the door looking sexy, hot, smell great, bottle of wine is in the chiller...

Hoda Kotb: What if the wife-- is working nine to five.  She's taking care of the kids.  She's doing all this stuff. Why is he running across the street to go sleep with Mary Smith?

Sarah Symonds: Two things.  Men are built differently than us, than women.  And also, communication. 

When the communication breaks down, and then the-- the passion and the intimacy disappears for whatever reason, then that's when the trouble starts.

Symonds says she knows all this because she's bedded many a married man. 

London lords, Hollywood celebrities and CEOS.  As a reformed mistress, she now gives advice to wives.  In her experience, where there's an unhappy husband... There's a woman slacking on the job.

Hoda Kotb: It sounds like what you're saying is a lot of this is the fault of the misses, the one who's being cheated on.

Sarah Symonds: I don't like to use the word "fault" or "blame".  There's three people in an affair, okay?  The wife has to take some responsibility.

Hoda Kotb: Do-- do you, when you're with a married man, do you think about the wife and the kids?

Sarah Symonds: Never.

Hoda Kotb: Really?  How come?

Sarah Symonds: Because actually, if you're in love with a married man, the wife and the children get in the way. 

Those words may sound heartless to anxious wives, and yet... She's not the only one advising women to take charge of their marriages, or take drastic steps to save them.

Gary Newman: I wanted to empower women and say, look, if you can just understand what drives men emotionally and romantically, you have a much better chance of putting your effort and energy in the right place so that you can develop a much closer relationship.

M. Gary Neuman is a nationally recognized family counselor and author of a how-to guide for worried wives.  He interviewed 200 men and offers a perspective on why men cheat and what women can do to prevent infidelity.

Gary Newman: Most men are not, you know, s-- waking up saying, "I got to find somebody else.  I got to get out there and I have to cheat." 

The truth, he says, is that most husbands are faithful to their wives.  The statistics even bear that out.  And those who aren't faithful aren't cheating for the reasons or with the partners you may think.  Just listen to what men told nNeuman about “the other woman” they fell for:

Gary Newman: It's amazing.  88 percent of the cheating men said that the mistress was not better looking and not in better shape than their own wives.  So--

Hoda Kotb: So just--

Gary Newman: --it's a myth.  This-- this-- she's better sexually, she's younger.  It's-- it's just a complete myth.

In yet another startling challenge to popular beliefs, Neuman found the typical cheater is not looking for an anonymous fling.  He told Neuman what he really wants is a woman he already knows: someone who can give him what he really wants.  And no, it's not what you're thinking.

Gary Newman: It's not about the sex.

That's right. 92 percent of men told Neuman they cheat because they're chasing something else.

Gary Newman: They are all cheating for emotional reasons.

Hoda Kotb: Meaning what?

Gary Newman: Meaning that they are feeling less than, feeling un-admired, unappreciated.  Feeling lost at home. 

Neuman's average man says he strays because he feels disconnected from his wife.  Instead of feeling like a loved partner, he feels more like an underappreciated servant expected to do house chores; tend to the kids and bring home the bacon.

Hoda Kotb: Now that sounds like the Flintstones to me.  That sounds like-- that sounds like at least the '50s or the '40s.  'Cause now every-- it seems like most households are two income households.  // it's a collaborative group effort.

Gary Newman: Then the message should be that both of us should be doing that for each other.   

So if I work really hard and if I spend time with the kids and my wife looks at me and says, "You want appreciation for that?  It's your job.  You're supposed to do that."  Well, she's right // But I-- I still want to know that the person I love most in life really thinks I'm great because of that. 

And when the men Neuman interviewed didn't get that positive feedback from their mates, they went looking for it in the arms of other women  - usually coworkers - who had already showered them with attention.

Gary Newman: They're looking for that friendship.  They're looking for that emotional attachment.

Hoda Kotb: But they're having sex with them, too.

Gary Newman: They are.  But the sex often is a further expression of the emotional attachment that they've had.

Which is why Neuman tells wives that regular sex with their husbands does matter.  That, and small gestures of appreciation  -- a love note, a romantic dinner for two  -- really can do wonders for both partners.

Gary Newman: A lot of these women who have put these ideas into practice, they don't report that their husband's taking more from them.  They report that, wow, my husband really is looking and say you know, what's going on here?  And he's liking it. And I'm receiving back a great deal of appreciation and affection.

That may work to prevent an affair.  But what should a woman do if she suspects her husband has already strayed?  This family counselor would tell her to take immediate -- and drastic -- action.

Gary Newman: Start checking his e-mails.  Start checking his cell phone.  You know, who he's calling.  What's going on--  his texts.  Get a GPS and stick it under his car so you know if he's really going where he says he's going.

Hoda Kotb: Okay, that sounds horrible.

Gary Newman: It is horrible.  It's horrible.  But if you think he's cheating, it's much more horrible for you to stick your head in the sand and just expect everything to come up roses.

But before you start playing amateur detective, consider chatting with a lawyer.  Neuman says proof is critical: Cheating husbands have told him they were more likely to admit their misdeeds when faced with the facts.  An exception to that rule:  Ed Hooke, who lied about his multiple affairs, even when confronted with the evidence.  Neuman says the good news for most women: men like Ed are in a league of their own.

Gary Newman: Well, these are guys that should never gotten married in the first place.  They're 12 percent of cheaters, who in my study said that that was going to happen no matter what.

Of course, men aren't the only ones cheating and lying about it.  Right now in America, a woman is about to put on her best dress for someone other than her husband.  But when she strays, will she be doing it for the same reasons a man does?

Over the years, movies and books have bred certain stereotypes about infidelity -- that it is always the husband who has the fling.  Take don draper on the cable hit mad men.

Draper: I'm married.

Woman: I guess I didn't ask because I didn't want to know.

There may be some truth to the old cliche. Studies show roughly 60 percent of the cheaters are men.  But the real headline? Almost 40 percent of the cheaters are women.

Joe Ussery: I wanted to throw the guy outa the house. 

This 33-year-old man says he picked up signs his wife was having an affair during a christmas party in 2006.  Joe says he saw his wife and a friend's husband getting cozy.  He says it was agonizing to watch.

Joe Ussery: And she's got her hands like, up on his hips.  She's lookin' up at him. And he leans down and kisses her on the cheek. I’m just like, "I can't believe they'd be brazen enough to do that in front of everybody like that." 

Joe and his wife had been married three years by then. But Joe says long before the party, he'd been feeling estranged from his wife.

Joe Ussery: It seemed like she was doing anything and everything she could to kind of distract from not just sex, but overall interaction together.

Weeks later, Joe says he found proof his wife was having an affair. The computer provided it -- as it so often has.  Joe says he found incriminating e-mails his wife had sent to her lover -- the guy he'd seen at the party.

Joe Ussery: It was like, seven or eight emails that I actually found that were--

Hoda Kotb: What were you-- what were you thinking when you were reading them?

Joe Ussery: I was thinkin' you know, "Damn it.  I knew it." 

He called his wife and told her he knew she'd been cheating -- although he didn't tell her he had proof.

Joe Ussery: And I just said, "I know you've been having sex with" and I said his name.  And then, it was-- "No, we're just kinda flirty."  Then, "Oh, we kissed once."  And then, "No, we kissed and groped once."  And then, "Oh well, we only had sex once."  And I already knew that was not true from the emails.  And it became obvious to me that she wasn't going to admit that she'd had a six-month-long affair.

Joe acknowledges he and his wife had marital problems before he suspected infidelity.  But even with counseling, the couple could not iron out their troubles.  He says he wishes her well, and accepts part of the blame for how things turned out. Their divorce became final this year.

Joe's ex-wife declined to speak to Dateline.

So why do women stray?  Experts say it is often because they too are looking for an emotional connection.

Gail Saltz: For women, the biggest sexual organ is the mind.  And that is what drives the infidelity, I believe.

Dr. Gail Saltz is the author of a new book about a woman's sense of her sexual self.

Gail Saltz: They want to be with a man who they feel understands them and emotionally connects with them.  And that is what's exciting.

For some women, that emotional infidelity is enough. Others move on to sex.  Either way, Saltz says, women often say having an affair is like doing a particularly intoxicating drug. And Saltz says there's a lot of truth to that description because the body does produce a chemical called dopamine.

Gail Saltz: That is what is released and exists in very high levels during new lust.  And it's very addictive. It is-- about repetitive excitement, risk taking, new experience. 

While Saltz and Neuman say that men and women stray for similar reasons -- because they want an emotional connection --  each sex finds its reward in different ways.  For many women, it's in the words whispered by a lover.

Gail Saltz: She is looking for a man to say, "I can't do without you.  You-- you are so hot and you are so incredible.  And we so connect on an emotional level that, you know, I have to have you." 

For many men, the reward is physical.

Gail Saltz: A man is --  is really enjoying the sexual act, the newness of being with somebody different and that is very intoxicating.

But science may soon be able to pinpoint the people who are predisposed to cheat.  And tell us who is lying -- and who is not.

Maybe the mysteries of the heart are not written in the stars, or the scriptures, or a hallmark card.  Maybe they're written in our dna.  Maybe some of us are born to be more faithful in love. And maybe, just maybe, we'll figure out why with the help of this little guy...

Larry Young: This guy is really important for our research because he's one of the few species that are monogamous. So this male when he mates with a female he forms a lifelong bond...

Dr. Larry Young is a neuroscientist with Emory University.  He's using a rodent called a “prairie vole” to help answer what makes humans bond and stick with one partner - or not.  It seems male voles and male humans may have similar chemistry going on in the brain, caused by a special gene.

Larry Young: At least in animals we know that it is involved in the formation of the bond between the male and the female. And we don't know for sure that it's happening in people but there is intriguing evidence that that may be the case.

But not every male prairie vole follows this script.  It turns out some have a variation in the “bonding” gene.

Larry Young: Have a much more difficult time forming bonds, and in fact, may never form a bond.  They're called wanderers. 

And that difference may be playing out in humans.  A 2008 Swedish study compared a singular gene among many men.  Some men had a variation in the gene.

Larry Young: What they found was, that a-- individuals with a particular variant-- were twice as likely to report a crises in their marriage in the last year.

And also, interestingly, the spouses of those people with this particular variant, express more dissatisfaction in their relationship.

Could a variation in a gene explain why some men are cheaters while others remain true?  It's possible.   It's also possible that a better understanding of how these genes work can lead us to a brave new world of matrimony, where science weeds out the potential cheaters.

Larry Young: If we believe that certain-- variation in certain genes can predict the quality of relationship that one has, then-- you may wonder why not-- genotype my potential partner.

Science has a long way to go before we can cherry pick our mates based on genes.  But maybe it is ready to help us figure out if the ones we have are telling us the truth...and nothing but the truth.

Steve Laken: It takes the brain a lot more energy to lie than it is to tell the truth.

Dr. Steve Laken runs Cephos, one of a handful of companies pioneering the use of MRIs for spotting deception.  The way it works is simple. Because telling a lie requires more blood flow to the brain, the machine may spot it.

Steve Laken: As the neurons in the brain are firing, blood flows to those neurons that provide-- energy to those neurons.  And that small amount of increase in blood flow, results in a small increase in the intensity of-- of the MRI. 

And today, a new client has come to test Dr. Laken's amazing machine: Ed Hooke.  He's admitted to four affairs in the past.  His wife Marie still doesn't believe he's made a full confession.

Step number one has Ed reviewing questions about his affairs.

Then he gets dressed and is ready for step two. The machine.  He's given the questions again via a computer screen inside the MRI. First, he's told to lie to all of the questions about his infidelity.  Then he's asked to answer the same questions again, this time answering truthfully.  A computer program is always measuring blood flow to the brain

Within an hour, the results are in. The image on the left shows him intentionally lying about how many affairs he had.  There's a lot of blood pumping in red, as should be expected.  The image on the right shows him answering the same questions truthfully.  There's less blood pumping.  That indicates less lying.  Good news for Ed.

Steve Laken: And our conclusion is that you were telling the truth on having only four affairs.  Okay? 

But Ed was also asked questions about his first affair, and how many times it was sexual.  This is what Ed told us about his first fling.

Hoda Kotb: You're saying in the whole year of the affair, you only slept with her once--

Ed Hooke: I slept with her one time.

Hoda Kotb: Is that true?

Ed Hooke: That is true.  That is very true.

Well, let's see.  On the left is his brain intentionally lying about how often he had sex with the first mistress.  The blood is pumping.  Now on the right. Ed's brain is trying to answer the same questions honestly.  That he had sex only once.  But here, there seems to be as much blood pumping.  That indicates lying.  Not good news for Ed.

So the conclusion is that...

Dr. Laken: --was that you were lying when you were saying that there was only sex one time and that it was just an emotional affair.

Ed Hooke: I disagree with that.  But, okay.

In fact, Ed is steadfast that the computer -- this time --has gotten it all wrong.

Ed Hooke: I will swear to the day I die, and this is not being deceived, and I will take these tests till the day I die to prove that I only had sex with xxx one time, and it was not intercourse.  And I will swear to that.

And yet, this new type of lie detector is considered more scientific than the old polygraph test, because it relies on computers, not subjective humans, to ask the questions and determine the results.  It's even being used in court cases.  For Marie, the lying test has raised new doubts.  Maybe he hasn't told her all the details of each and every fling.

Marie Hooke: It makes me just wonder about other things in general that I don't know about to ask questions about.  That there could be lies and deception that I have no way of knowing.

Now Marie has a decision to make.  Should she still try to salvage her marriage?  Given this show of truth and lies, is there anything left to save?

Hoda Kotb: Do you think that your marriage can be repaired?

The way you view marriage and infidelity is a bit like peering at Rorschach tests... Everyone sees something a little different in those dark stains.  How many affairs are too many to get past?  How many lies before the hill becomes insurmountable?  The answers are often different for every couple.

Gary Newman: People repair their marriage even after multiple affairs.  It can happen.  So your marriage isn't over until it's over. 

But family counselor M. Gary Neuman says, in his experience, there is one thing every cheater ultimately must do if he or she really wants to repair the marriage they've shattered.  Come clean.

Gary Newman: Whatever I need to do-- if I have to apologize to you 100 times, if six months later you still want to look at my cell phone, I understand 'cause I-- I cheated.  And chances are, I lied to you and drove you crazy.

But what happens when a spouse won't come clean?  For most of their marriage, Ed Hooke hid his affairs from his wife Marie.  But now, Ed insists he's told her the everything.  He even took a new type of lie detector test to prove he's no longer cheating.

Ed Hooke: It's like I'm finally to the point where I-- I want to be honest.  I want to be the way that I'm supposed to be.

So, is there a future still for Marie and Ed, the couple?  He's hopeful.  She's not.  She believes over the past two years she gave Ed more than enough chances to tell the truth.  Maybe too many chances.

Marie Hooke: I think a year and a half ago, we very much could have made this.  Now it's quite possible that the mountain is just too big between us.

Marie, after years of feeling like a victim, now feels much stronger.  She helps run a Web site,, where she shares her story with other betrayed spouses. 

Marie Hooke: if you're judging a couple that's trying to survive infidelity, think again.  Because you can never know what you're going to do until it happens to you

That brings us back to Angela and Marshall Sanders.  Four years ago she found out about his affair.  On that day of truth, they both thought the marriage was over.   But then, Marshall had an epiphany.

Marshall Sanders: God was sayin' to me, you can be single, you can have young girls, you can do all that stuff.  But it won't be with her.  And-- you know, in response to him sayin' that to me I made the decision that I did.  (sniffle) I knew that I would have to change.

Hoda Kotb: That was a huge spiritual moment for you, wasn't it?

Marshall Sanders: Huge. Huge.

First he had to take a good hard look at himself.

Marshall Sanders: I mean, I had to totally-- and look at some of the not-so-nice things I've done and had to say to myself, "You know, I've been at times a horrible man." 

He knew it was one thing to say he was going to become a new man -- and another thing entirely to make that happen.

Marshall Sanders: When I was a basketball player in college, I would do whatever it took, you know, to become good, that was what I was known for. And I said, "You know, what?  I'm gonna, you know, give that much commitment to my marriage,” and that's what I decided to do.

But saving his marriage wouldn't be easy -- and it wouldn't be quick. In those early days, Angela was angry -- and hurt.

Angela Sanders: And, I can remember tellin' Marshall, I-- I can the even pray right now I'm so hurt.

And-- he said, "I'll pray for you.  I'll pray for both of us." 

Not only did he pray for both of them, he began sending her text messages when they were apart telling her he loved her. He left sticky notes for her in the morning. And together they saw a marriage counselor as well as a spiritual adviser.

Hoda Kotb: So you guys had had-- you guys were openly discussing what had happened.

Angela Sanders: Oh yeah.

Hoda Kotb: You were-- you were-- you were doing everything right.

Angela Sanders: Yes.

Their experience shows marriage can survive infidelity.  But an expert counselor doesn't ensure a happy ending.  Scientific innovation can't force marital change.  Even the best how-to guides cannot fix what infidelity breaks.  To do that, a couple has do a lot of hard work on their own.  Angela and Marshall have found that out together.

Hoda Kotb: Do you-- fully trust him?

Angela Sanders: I would love to be able to say I trust Marshall a-- 100 percent.  I'd say probably 99 percent.  I-- I-- I've got a-- I've got to give something over to the flesh.

Hoda Kotb: What about from your perspective, Marshall? Do you trust yourself that you won't-

Marshall Sanders: Absolutely.

Hoda Kotb: --do it again?  You do?

Marshall Sanders: Absolutely.  Absolutely.

But to get to that point, they had to start over.

Angela Sanders: I guess, one of the best analogies in my mind, was-- you know, we were in this beautiful house, and that house burned to the ground.  And, so we had an opportunity to-- to rebuild, but we needed to fix the foundation, 'cause obviously there was a crack in the foundation.