Recently, evolutionary psychologists have turned their sights on love and divorce. It didn’t take them long to notice that when people fall in love, there’s a period of up to three years during which the zeal and infatuation ride at a peak. The internal signals in the body and brain are literally a love drug. And then it begins to decline. From this perspective, we are preprogrammed to lose interest in a sexual partner after the time required to raise a child has passed—which is, on average, about four years.40
