By Samantha Cleaver
So you found "The One" and you're deep into relationship-building mode. Nothing's better at derailing "till death do us part" than an "accidental" date or a roll in someone else's hay. We've heard all the excuses: It just happened. I didn't see it coming.
Think it's just about sex? Not so fast. When marriage therapist M. Gary Neuman interviewed 100 cheating men for his book, The Truth about Cheating, only eight cited sex as the main reason for their infidelity. Forty-eight of them said emotional issues drove them to cheat. If sex was a factor, other problems were probably lurking.
Knowing what makes men stray and how to squelch those urges can help keep you and your chosen one happy for the long haul. Tapping new research in genetics, economics, anthropology, and biology, as well as our experts' advice, we've developed this guide to the causes of infidelity—and what you can do to make sure the home fires blaze hot enough to keep you happy.
You're a Dirty Rat
Well, not a rat, exactly, but a vole—a prairie vole. This small rodent is one of the few mammals that actually bond with their mates, and a vole's genetic traits give scientists clues about why humans stray from theirs. It turns out there's a switch inside the brain that controls the desire to form close ties. Emory University psychiatry professor Dr Larry Young has found that switch in voles: It's a gene that regulates the release of vasopressin, a hormone that activates receptors in the brain to regulate behaviour.
In male voles, vasopressin helps keep the mate close and the competition far away. Assuming that what's true for voles is also true for humans, vasopressin activates bonding centers in your brain, making you feel attached and protective. (In women, oxytocin serves the same purpose.)
But according to scientists at Stockholm's Karolinska Institute, if you have a certain variation of the gene coding for one type of vasopressin receptor, you won't be as affectionate and cuddly as your mate would like you to be. The 2008 Karolinska study found that with this version of the gene, you're less likely to commit and twice as likely to report recent relationship problems.
Having the gene variant isn't a get-out-of-jail-free card, however. Your culture, childhood, and other life experiences play a large role in determining your behaviour, Young says. "This gene changes the probability of the type of relationship you'll have; it doesn't determine it," he explains. "So you can't ever say you're genetically pre-determined to cheat."
Keep the faith: To ward off any such probabilities in your own relationship, increase your intimacy to boost bonding. "We know that vasopressin is released during sex," says Young, "and it's probably released in other intimate situations as well." Make sure your vasopressin receptors are firing throughout the day by creating what Neuman calls "touch points." Commit to making five small, intimate gestures—a hug, kiss, e-mail, or text, for instance—throughout the day. As she responds with five of her own, you'll ignite the vasopressin bonding centers in your brain at least 10 times each day.
You're Not Risk-Averse Enough
For many men, cheating is simply another decision, one with its own set of costs and benefits. Infidelity has uncertain and individual outcomes—you don't know how guilty you'll feel afterward, whether or not she'll catch you, or exactly what you'll lose in a divorce—so economists Dr Edinaldo Tebaldi of Bryant University in the US, and Bruce Dr Elmslie of the University of New Hampshire in the US, have developed a model that identifies some of the factors influencing a person's decision to cheat.
Their study, published in 2009, reveals that men and women use drastically different decision-making processes. What's she thinking? A lot. Is he worth keeping, or is there someone out there that might be worth the risk of leaving? Just how much (money, love, companionship, security) will I lose if I get caught spending my lunch hour in a seedy motel? It's about her relationship, her future, and the investment she might lose if she's caught.
What are you thinking? Not much: Is there an opportunity, and will I get caught?
Keep the faith: Make an informed decision by figuring out what you'd be losing now and in the future, Neuman says. Once you realise the risks, start sticking around the house. More than half of the men Neuman interviewed spent time away from home before they cheated. "They started working later, scheduling more business travel, or hanging out with friends," he says. While you're at home, do something few men do when they find their eyes roving: Face your spouse and admit to her that something's wrong. "Tell her, 'I'm looking around and I shouldn't be,'" Neuman says. "Then figure out, with her, what can you do to make the relationship better. Once you know what's wrong and how you'll fix it, saving your marriage will replace thoughts of cheating."
You Don't Recognise Threats
When they're surrounded in social situations by what researchers call "attractive alternatives," men tend to let their guard down too much. In a study done by McGill University in Canada, men and women who were presented with a virtual-reality assessment reacted very differently when they were asked to evaluate a group of photographs that included an image of an attractive person of the opposite sex. Women avoided the photo, but men didn't. Asked to imagine an interaction with an attractive classmate of the opposite sex, women increased their thoughts of commitment and threat. Men (drum roll) didn't.
The McGill researchers suspect that women strive to be protectors and gatekeepers of their relationships, or that they view threats to their relationships as personal. (Men, on the other hand, tend to be more individualistic; they don't define themselves by their relationships as much.) Either way, women use if-then contingencies—if he comes over here, then I'll excuse myself to get a drink—that spark automatic defense mechanisms when they see an attractive alternative moving in.
Keep the faith: Take a page from her playbook and develop your own if-then plan. The McGill researchers found that when men do this before entering a situation with lots of potential other women (if Susan comes over here, then I'll head for the men's room), they're more likely to perceive and ward off threats.
Your Banter is Off
Want to find out how likely you are to cheat? Start counting the number of times you two snarl at each other, and the number of times you smile. When Dr Elizabeth Allen, an assistant professor of psychology at the University of Colorado in the US, reviewed communication between partners about to get married, she found that those with lower ratios of positive-to-negative behaviours were more likely to cheat in the early years of their marriages. Couples with a 2.4-to-1 ratio of positive interactions (eye contact, nodding, smiling) to negative ones (scowling, eye rolling, expressing contempt) before marriage were more likely to experience infidelity after the wedding than couples with 4-to-1 positive-to-negative ratios.
It wasn't that these partners didn't like each other—at the time, they probably thought they'd be living happily ever after. But the mates who didn't cheat down the line had many more positive interactions before marriage than those who cheated. "The way you interact and the more positive you are, the more you seem to be buffered from future risk," Allen says.
Keep the faith: Boost your ratios—whether you're just dating or already married—by keeping contemptuous words, criticism, stonewalling, and defensiveness to a minimum, Allen says. Even if you're not feeling great, try to increase your positivity, encouragement, and collaborative problem-solving, and look for things you can agree on. In her study, Allen observed behaviours like smiling, nodding, and saying things like "I agree," "I understand," and "good point" to be helpful. Other researchers have found that even happy couples sometimes enter negative territory, Allen noted, but they break themselves out of it quickly. If you find yourself in an argument, acknowledge her point of view and try to find a compromise. The more you do this, the more she will, too, and, well, the happier you both will be.
You're Not Challenging Each Other
It takes more than sex to keep partners engaged, says Dr Gary Lewandowski, an associate professor of psychology at Monmouth University in the US. We need our partners to challenge us and (to quote Jerry Maguire) complete us. "We look for relationships that make us better people," says Lewandowski, "and we're looking for partners who will be able to improve who we are."
Lewandowski calls this process "self-expanding." But the precise amount of self-expansion you need from a spouse or girlfriend is subjective, says Lewandowski. What's more important is determining whether or not that dynamic exists in the first place. In his recent study, Lewandowski found that partners who felt their mates weren't providing them with enough excitement to make them better people were more aware of opportunities and alternatives, paving the way for cheating.
Keep the faith: Are you sitting around waiting for her to challenge you? So's she. "You can't be a passive participant in your relationship, waiting for your partner to dazzle you," Lewandowski says. "It's a two-way street." If you're frustrated with your self-expansion, let her in on the secret. Put yourselves on the same page by making self-expansion part of your everyday conversation, says Lewandowski. Then set goals that can help you both expand. Ask her to help compensate for your weaknesses by teaching you something—how to make that homemade pizza crust that you love, for example. Or offer to teach her something new, like the new move you've been practicing on the soccer field. Then sign up for a mixed team together so you can both try out your new skills.
And make future plans—pick up tickets to a show neither of you have heard of or book a cheap flight to somewhere you've never been. Pulling off moves like these will ensure that you're pushing each other in the right ways—and always will be.