"People who have cheated in the past usually can't handle being so close with one person. But that's exactly what happens in that first year of marriage -- you get closer, you plan for the future, you focus on the togetherness and the partnership," Weil says. "So someone with commitment issues might feel even more trapped, and be more compelled to cheat, using another person as an intimacy blocker to keep themselves from getting too close to their spouse."
John, the pharmaceutical rep who cheated after having been married for a year, says he had always cheated on his girlfriends. "I honestly think it's just the way I'm wired, like a lot of guys."
How to cheat-proof your love: Your best bet is not marrying a guy who's at high risk for straying. In addition to our checklist , Houston offers these warning signs: an extremely active sex life, a lot of female friends, a lot of male friends who cheat, and parents (a mother or father) who cheated.
* Names and details have been changed to protect the sources' anonymity.
Before you take your vows, scan this surprising list. The more items you can check off, the less likely he is to be checking into a hotel with someone who's not you.
He doesn't hide his animal lust
If he openly drools over your best friend's lower-back tattoo, laugh it off. It's when you find a photo of said tat on his camera phone that you need to worry. "In every relationship, people window-shop," says "Women's Health" advisor Yvonne K. Fulbright, Ph.D., a certified sex educator and the president of Sexuality Source in Washington, D.C. "But trying to hide it means he might be thinking about acting on those urges."
You're his better-looking half
Unattractive men might cheat too, but according to a study published last year in the "Journal of Family Psychology," your chances of marital bliss are better if you're the beauty and he's the beast. Of the 82 newlywed couples surveyed, those in which the bride was easier on the eyes reported the most satisfaction.
He cries at sappy movies
Sure, few guys besides Dr. Phil talk much about their emotions. But if he consistently avoids heartfelt conversations, heed the signs. A 2008 study from the University of Montreal discovered that the more emotionally detached your partner is, the more likely he is to cheat. "That's because habitual cheaters only care about themselves," says sex therapist Gloria Brame.
You don't always agree
No two people see eye-to-eye all the time, so if a couple never fights, it usually means one of them is suppressing feelings that can build into resentments they'll use later to justify straying, says couples psychologist Don-David Lusterman, Ph.D. "Being challenged can be an aphrodisiac," he says. Not to mention that make-up sex is always worth it.
He goes to church
If you want him to worship you, research shows, it's better if he worships, period. A study published last year in the "Journal of Marriage and Family" found that regular churchgoers were less likely to have affairs, regardless of their faith.
He's got a small...paycheck
An msnbc.com survey found that more men earning $300,000 or more a year admitted cheating than those who earned less than $35,000.
More from Women's Health: