I think you answered yourself, you said he was someone who had to be in a relationship and, that being said, you are probably the only woman he has gotten to put up with his bad behavior? You give him what he wants when you are with him, you put up with him.

What do you want? Do you want someone to hang out with that otherwise is a nasty companion or do you want to look further and find out someone enjoyable to try a relationship with?