Denicat, it sounds like he is one of those people who derives satisfaction and an illusionary sense of self-worth by provoking others into desiring him. Maybe he feels alive and wanted and safe when others find him sexually desirable. This happens a lot with people who are sexualized as children, either by abuse, inappropriate speech by surrounding adults, jealousy of a parent, etc. Or maybe he's simply a narcissist, and is unable to really engage in a real relationship -- he must rely on this dance to feel safe.
Well, there I go, after saying don't bother analyzing!
It doesn't really matter what his problem is, though. You are the important factor here. You must take the actions that you know are right in order to protect yourself and to create a loving, mutually beneficial relationship with a person who is actually available for one.
Best wishes to you, and please keep us posted.