I believe the answer is: Women's approach to sex is more relational and men's more recreational. In our ancestry, women most often sent their genes into the future by pairing wisely, and men by pairing widely.
These approach would most likely influenced by each gender's involvement in reproduction process. Women had to carries the fetus for almost a year. In that time, they would be in pain and their movement are extremely limited. Which is why paring wisely is a best way to obtain protections under that situation. Men on the other hand, only biologically involved during the sex.