Whether you’re a man or a woman, if you’re in a committed relationship, then there’s a good chance that you don’t want your partner to be lured away from you by another person.

And as it turns out, “chemistry” is important to your relationship in more ways than one.

In fact, the secret to fidelity involves making your partner’s body produce a “love” hormone called oxytocin, a new German study suggests.

You’ve probably heard of oxytocin—women produce it, for example, during certain activities such as childbirth and breast-feeding, and it makes them feel more bonded and attached to their children.

But both sexes produce the hormone—and there are various ways to keep it flowing…

THE FIDELITY HORMONE

For the study, researchers gathered single heterosexual men and heterosexual men who were in committed relationships. Half of each group was given a nasal spray containing oxytocin and the other half was given a placebo nasal spray. About 45 minutes later, each of the men was asked to stand in front of an attractive female stranger.

Researchers wanted to measure how much distance the men kept from the women, because prior studies have found that the less personal space you keep between yourself and a person of the opposite sex, the closer you feel to that person—a small gap signals intimacy and possibly even romantic interest.

Results: Men in relationships who were given the oxytocin stood farther away from the women than the men in relationships who were given the placebo. Among the single men, the oxytocin had no effect. Then researchers performed a similar experiment, except instead of having each male participant stand in front of a woman, each participant was told to stand in front of a man. In that experiment, the oxytocin had no effect on anyone.

In other words, the main finding was that oxytocin made men in committed relationships stand farther away from attractive women they didn’t know. And what can we take away from that? Well, according to the researchers, it implies that these men may have been signaling to the woman they were not romantically interested. Now, the researchers can’t say that oxytocin will necessarily make men 100% faithful to their partners, of course, but they argue that the less often committed men signal romantic interest through body language, the less likely they are to stray, said the study’s lead author, Dirk Scheele, MSc and doctoral candidate. Though this study involved only male participants, Scheele told me that the hormone works similarly in both genders, so oxytocin may help prevent women from cheating on their partners, too.

GIVE YOUR PARTNER AN OXY BOOST

If you want to boost your partner’s oxytocin levels, you could go buy a bottle of oxytocin nasal spray online on a site such as Amazon.com. But increasing oxytocin exogenously(ingesting more to increase your body’s supply), such as through a nasal spray, hasn’t been studied in the long term. We don’t know what dosage would be best…or how long its effects may last…or whether it will truly make a partner faithful….or what the long-term side effects may be…and the quality and purity of products on the market is hard to determine.

So in all honesty, would you really ask your partner to use such a spray?

So, in the hope of preventing any adulterous impulses, there are other things that you and your partner can do that will boost your partner’s oxytocin levels endogenously(naturally). And the best part is that they’re all pleasurable, and you may boost your own levels of oxytocin in the process. Here is what you can do with your partner…

Have sex often. Oxytocin is released during orgasm, and orgasm boosts oxytocin more than anything else.

Cuddle often. Gentle, loving physical contact, such as cuddling, kissing, hugging or receiving a massage, can all increase oxytocin levels. Even just holding hands while you walk or putting your arm around the other person does it, too.

Share your feelings. Telling your partner that you love him or her will make your partner feel warm and fuzzy inside, which raises oxytocin levels. A small act of kindness, such as a sweet e-mail or text that says “thinking of you” also can do the trick.

Watch an emotional movie together. Renting a romantic film that’s emotionally compelling makes oxytocin surge because you empathize with the characters and feel the love that they feel. Research shows that this one simple action makes oxytocin spike 47%. (Do this while cuddling for a double whammy of oxytocin!)

Go karaoke singing. Believe it or not, belting out a duet with your partner can cause oxytocin levels to elevate—it’s because you’re aware of feeling joy simultaneously, which connects you more deeply.

Dance as a pair. Dancing with your partner in a way that you hold each other closely most of the time and move in step with each other is an oxytocin booster—in fact, research shows that one night of dancing makes the body produce 11% more oxytocin.

Get scared together. Doing something thrilling together, such as going white-water rafting or even riding a roller coaster, may help bond you even more and increase oxytocin because an experience that frightens you a little and triggers an adrenaline rush tends to make you cling to the person next to you a little more, both emotionally and physically. There’s a shared feeling of “We’re in this together, and we’re going to make it through.”

Source: Dirk Scheele, MSc, doctoral candidate, department of psychiatry, Neuromodulation of Emotion (NEMO) Research Group, University of Bonn, Germany. His study was published in The Journal of Neuroscience.