Females evolved pleasurable response to sex as a survival mechanism to deal with rape, much as males evolved the same to encourage it -- certainly long before humans ever arrived on the scene.
Men evolved to compete with each other and then seize women as prizes, to force themselves on their prizes, and then develop a sense of emotional attachement to their prizes. Meanwhile women developed to enjoy being captured, and to take advantage of the emotional attachments that the male developed to enlist his aid in child-rearing.
It's pretty ugly yes, but it's there. And if you don't understand that men (all men) have that drive to varying degrees, to just take and let the consequences sort themselves out, then you'll never understand why men can get so angry at women that they will beat them to death for not consenting to sexual relations.
I really am not sure that's something I would WANT to understand...
Don't start with the "you manhater" BS. I think we can all agree this crap is insulting to both men and women.