Those couples wishing to re-spark their romance need only to look to modern chemistry. A recent study strongly suggests the pituitary hormone oxytocin drives feelings of monogamy in men.
The study, published in the Proceedings of the National Academy of Sciences, hooked men to a functional MRI machine, misted men them oxytocin and then showed them photographs of their loved one intercut with photographs of an equally attractive woman and pictures of houses. A second group of men received the same test, but with a placebo mist in place of the oxytocin. Following this test, the subjects then filled out a questionnaire to gauge their passion and attraction to their current partner. The collected surveys show men sprayed with oxytocin felt stronger passion for their current partner than their non-oxytocin counterparts.
The MRI brain scans of the oxytocin men reinforce the survey data. The areas of the brain associated with reward lit up when given the combination of oxytocin and their current partner. Furthermore, a similar study showed that men given oxytocin mists will sit further from potential future mates in social situations.
Monogamy is rare among animals. The brains of monogamous animals, such as humans and prairie voles, have more oxytocin and dopamine receptors. Dopamine is a hormone associated with reward and is often released when oxytocin levels are elevated.
Oxytocin is naturally released by physical contact and proximity from a partner. Foot rubs, hugs, kisses and sex all flood the brain with oxytocin. Therefore, this new science suggests the best way to keep a man from straying in a relationship is rather simple: sex.
The answer may seem oblivious, but science has finally confirmed the best way to keep a man from having sex with another woman is to have sex with said man.