SIGN: HE EARNS LESS THAN YOU...
Men who are financially dependent on their wives or girlfriends are five times more likely to cheat than men who contribute an equal amount of money to the relationship, according to the 2010 Cornell University study. Researchers theorize that some men who feel like financial failures look to sex with multiple partners as a way to shore up their masculinity.

Protection Plan: If your man is a stay-at-home dad or a struggling student, make a special effort to help him feel that his non-monetary contributions to the relationship are invaluable. Good: "Honey, this dinner is delicious." Not so good: "That apron you're wearing really brings out the color of your eyes."

SIGN: HE'S NOT FEELING CONNECTED...
Work. Kids. Bills. Sometimes life gets so hectic it feels as though you and your man are business partners instead of lovers. Emotional, not sexual, dissatisfaction is the number one reason men give for cheating, according to Neuman. "A man needs someone to love and appreciate him," he says. "If that's not you, he's more likely to find it somewhere else."

Protection Plan: If your passionate good-bye kiss has been replaced by a "see ya later," it's time for a change. Neuman advises couples to make a priority of spending time together. His study found couples who spent at least 30 uninterrupted minutes a day together were significantly happier than those who didn't.

SIGN: HE'D RATHER GO IT ALONG THAN SEEK YOUR SUPPORT...
"Some men have trouble communicating their disappointment," says Chad Dion Lassiter, professor of race relations at the University of Pennsylvania School for Social Policy & Practice. "So when he's faced with an obstacle like racism or he doesn't get the promotion or he loses the deal on Wall Street, his hyper-masculinity won't allow him to sit and cry or pray. Instead he gets his power back conquering women."

Protection Plan: If you notice a change in your man's demeanor -- for instance, if he seems withdrawn and anxious -- he might be dealing with a challenge that he doesn't know how to talk about. Sometimes gentle and loving probing is all it takes to get your man to open up.

SIGN: HE'S A NARCISSIST...
Does your man think he's so wonderful he deserves special treatment from the world? Does he care little about your feelings and loves to be the center of attention? He may be a narcissist, explains Chapman. "Narcissists are driven by their egos. They need women to idealize, admire and be in awe of them," she says. "And they are going to cheat 99 percent of the time."

Protection Plan: "If your man is a narcissist, understand that you're dealing with a serious personality disorder even therapists can't cure," counsels Chapman. Unsure if your man fits the profile? Consult a professional.

SIGN: HE'S NEVER BEEN IN A SERIOUS RELATIONSHIP...
It can feel as though you've struck gold when you meet a single man of a certain age who doesn't already have an ex-wife and a couple of kids. But if he's in his forties and has never been in a serious relationship, it may be a warning, says Chapman, host of Sirius XM's The Audrey Chapman Show. "Some women want to believe their love is so powerful that even if this guy has never committed to anyone, she will be the exception to the rule," says Chapman. "But this is a man who will cheat to keep himself from getting in too deep."

Protection Plan: If he's commitment-phobic, it's okay to date him, but keep your eyes;and options;open. He may not turn out to be your Mr. Long-Term, and there's no reason to focus on a romance that might be on the slow train to nowhere.