I think he is staying with you until he sees something better come along. He doesnt have to commit anymore and you are his close friend that he feels comfortable with but he is a guy and he will be in it until he finds another girl then he will wonder why you are taking it so hard because you were in an uncommitted relationship. Believe me I have been through them all, included being that guy with a couple of my girlfriends. We stay in it because its what we know, till we see another girl who takes interest or visa versa. Its terrible but thats the way it is unless you set the ground rules and put him back in his place.