Everything you mention is valid and apply to both men and women, however, this doesn't explain the disproportional need for men to have sex. So women would want a sexual relationship as part of a healthy loving relationship. But for men, it is a mandatory need that must be met while it is a "nice to have" for a women. The real question is why would any women participate in hook up culture where you are literally being used as their "toilet of the day."