Why Men Cheat

How often do men confess to cheating on before being caught? Only 7 percent of men who strayed told their wives without being asked. Fifty-five percent of men in Gary's study have either not told their wives or lied after being confronted with hard evidence. "I kind of tell people, 'If you're going to wait for him to come tell you, go buy a lottery ticket, because you like playing against the odds,'" Gary says.

In 2004, Colleen discovered that her husband, Scott, was having an affair and says she caught him several times. The first time she says she caught Scott was on Father's Day when the other woman called the house. "I was standing there right with him in the kitchen so I heard her, and she said, 'Are you okay? Are you okay? Hang in there,'" Colleen says. "He tried to tell me it was a dispatcher from work and that was very suspicious."

Colleen says Scott's affair was painful, but the lying was worse. "When you've been married for so long and you trust someone so much and they look you right in the eye and they're telling you a lie, it takes a lot to move past that," she says.

Gary says Colleen's desire to believe her husband is common. "The problem is that that's the moment where every woman has to look at her husband and say, simply, 'Look. The fact [is] that I think you may be cheating. I'll trust you at your word. I've got no choice. But there's something wrong with us.'" Gary says.