Most Helpful Guy
I think he's nervous. If you've already been on dates, you could probably just call him boyfriend and he would go with it
Most Helpful Girl
Maybe he already sees you as his girlfriend and doesn't see why he has to formally "ask" you. Or he is really just into taking it super slow to make sure he is really in it. Some people take relationships incredibly seriously so then they really want to make sure 100% that it is something they want in the long run
There is nothing wrong with asking him for clarity. You also deserve to know where you stand exactly.