Should I give up?

This year my love life has ben terrible. I find that when guys first meet me they want sex. Whats worse is that I've been there for this guy around 4 years, and more than most of his family yet whenever he gets his stuff together he gives another girl the title. I'm one of the few people he could actually reach out to in jail, even after I've put up with all of his crap. We had a relationship in the past, but we both stopped trying at one point and it didn't work out. I'll always love him because I've been a friend first. Sometimes he sais he loves me and I believe it because he's not a liar. But then there are times when he wont say it and I''m not sure if he just wants to hurt me or is actually telling the truth. Should I just leave him alone? I don't want this to become a pattern for the rest of the guys I date but it already has. I'm just tired of being ignored