I'm not blind to the ways men and women approach sex differently, but the point is, men and women make relationship decisions that are mutually acceptable if not beneficial to both for their own reasons. To say that one is merely using the other if a couple lives together before marriage is overly simplistic and under estimates the responsibility both people have for their own actions.
Note that I never said in all (at least I don't I ever said in all). I said in most cohabitational situations the guy is using the woman. I stand by that.