Why is sex more painful for women than men?

Usually anyways. Well, think about it - Women have hymens and losing your virginity can be extremely painful (depending on the girl.). If a man's penis is "too big" it hurts like hell. Anal, is very painful to some women. Oral hurts if it's big or even if the guy is forceful (which from what I've heard a lot are.). So, why do women experience these kind of pains during sex and men experience little to none? Another question, why do a lot of men seem to get-off more knowing women endure these pains?