I've heard that he is a player. Players act the part in relationships to get what they want out of you. They may make some concessions along the way to gain your trust, but when called upon for something substantial, they often dump their victims.
Some players can be fun in a noncommittal, casual relationship.
They're still adolescents who haven't grown up yet. Some of them may have more serious character pathologies. They'll use you up and spit you out with no remorse. Sometimes, the damage they inflict cannot be undone. In either case, you're probably wasting your time if you're looking for a meaningful relationship.