I think most people are motivated to want to do what is best for themselves. People want to avoid STDs. I believe in a system that leaves it up to the individual to protect their own health.
As far as sex slavery goes, in Canada, if the woman has a Canadian accent, I'm confident that she hasn't been trafficked and forced to work as a prostitute.
The counter-argument would be, so what if my sexual relationships are superficial, one can still have satisfying and rewarding relationships with friends, or parents, or siblings, or whatever.
When you're in a relationship, the dynamic seems to change over time. I only had two long-term girlfriends, but with both of them, as time went on, the sex tapered off in terms of frequency. We had sex less and less often. And talking with friends or whatever, hearing other people's stories, that seems to be the case with a lot of romantic relationships.