Places a personal ad online, to meet friends. That's asking for trouble, in my opinion. Only if I had a say in the matter would I be comfortable. 4.5, those are MY parts to gaze upon, unless I gave my blessing. He'd be even stricter with me, I know.
Romantic context is the asskicker there.
It would have to be thoroughly discussed and a clean break. The Boy had an addiction once, then gave it up, and now dabbles occasionally. He claims that he doesn't fantasize about the women themselves, but the sex acts that take place and that it fuels his fantasies with me. Which is alright, provided that the Porn Girlies don't take my place and he completely forgets that I'm the one there. 2.5 -5 depending on what happens with that.