The world is full of temptations. Sexual temptations. But evolution invented something that self-restrains us from biting the bait when opportunity arises. A new research published in the journal Evolution and Biology explains why people in stable relationships often ignore the chance for a little sexual diversification, even if they can get away with it.

Psychologist Gian Gonzaga, an eHarmony research scientist, put 60 heterosexual undergraduates at the University of California in Los Angeles, involved in relationships for at least three years to watch photographs of an very attractive person of the opposite sex (male or female), coming from eHarmony, a popular dating site. The subjects wrote a 5-minute essay describing what they found sexy at the person in the image, then they were assigned into three groups.

The first group had to write an essay describing the moment when they had experienced the strongest feeling of love for their current partner, while the second group had to remember their most memorable and intense sexual encounter. The third category were allowed to write about whatever they wanted.
All the subjects were asked not to think about the persons they watched in the photographs while composing their essays. Each time the temptation came into their mind while making the composition, the subjects had to tick a box.

Those put to focus on their love for their partner were three times less likely to think of the sexy temptation than the group put to describe the best sex they had with their long-term partner. Those from the third group could not clear their mind of the image of the hot person, ticking the box six times more than the first group.

"Feeling love for your romantic partner appears to make everybody else less attractive, and the emotion appears to work in very specific ways by in enabling you to push thoughts of that tempting other out of your mind," Gonzaga told a UCLA newsletter.