At the start of a piece on the porn classic Deep Throat, Laura Kipnis muses on Mother Nature’s shocking lack of gender solidarity in arranging things so that, on average, it’s easier for men than women to arrive at the Big O:
And let’s not forget the unkindest joke of all, the placement of the clitoris–the primary locale of female sexual pleasure–at some remove from the vagina, the primary locale of human sexual intercourse. While not an insurmountable obstacle, some percentage of the male population still has yet to fathom these anatomical complexities. Why wasn’t everything just combined into one efficient package, as with the lucky male?
Utter speculation here, but a guess: For reproductive (and therefore evolutionary) purposes, the male orgasm is the strictly necessary one. If someone’s going to go first, then, it’d make sense for it to be the guy. If caveman finishes first, rolls over, and goes to sleep, pregnancy can still occur. Not so much the other way around. And if cavewoman’s still aroused but hasn’t had her turn, well, added incentive for a post-refractory second round. Not exactly fair, but it’d make a certain amount of evolutionary sense.