Most Helpful Guy
He'll probably be expecting it. As someone who moves very slowly and isn't really interested in a relationship right now, I always have girls who I'm seeing ask me the question at some point. Some have even broke down crying whilst asking me and I always give the most truthful answer.
Most Helpful Girl
If it has been 6 months and he still hasn't made the move to ask you to be his girlfriend, he isn't serious about you and has no intention to be. Think about it this way, why would a man call you his girl but not care to make it official. Do you see how confusing that sounds? He is just telling you what you want to hear to get something out of you.