Love.
There is no doubt that the purpose of life for humans is love, both scientifically and empirically. All mammals seek out partners at one point or another. When boys reach puberty they get non-stop
erections. They even get involuntary erections known as morning wood or
morning glory. All these erections are in anticipation of finding a partner to have blissful encounters with. When girls hit puberty, they subsequently frequently get wet around the vagina to facilitate sexual intercourse. Their uterus also enlarges to enable pregnancy.
Empirically, love is also the most important thing that drives humans, for instance with parents, who unconditionally do anything for their children. In conclusion, human
physiology has evolved for love. Human characteristics evolved not only for mating partners but also to be social.
In other words, love is what makes the world
go round