While it’s true that nobody can really predict how long a romantic relationship between two people will last, there’s this one objective predictor that could determine the longevity of your union. We're talking about your hormone level, or more specifically, your levels of oxytocin, aka the cuddle hormone.

Psychology professor Ruth Feldman from Bar-Ilan University in Israel has found that "couples who stay together have higher levels of oxytocin in their blood when they first pair up than couples who ultimately break up." For their study, they measured the oxytocin levels of 60 couples and found that couples with the highest levels of the hormone were still together six months after the start of the study.

"These findings suggest that [oxytocin] in the first months of romantic love may serve as an index of relationship duration," they wrote.

Meanwhile, Rene Hurlemann, M.D., a professor of psychiatry at the University of Bonn, in Germam says that a reward is considered as the strongest element for motivation. "Sexual monogamy is actually quite costly for males, so there must be some form of mechanism binding males and females together, at least for some time." Another study found that oxytocin allows positive social interactions and the development of bonds.

So how do you release this hormone? Larry Young, a professor of psychiatry at Emory University in Atlanta says you release a lot of dopamine and oxytocin when you get intimate with your partner adding that, "it’s creating that link between the neural systems that are processing your facial cues, your voice and the reward system of a partner's brain."

PHOTO: Flickr Creative Commons/Sean McGrath