College guy: does he still like me, you think?

We're both college freshmen who didn't know each other before the end of August when we moved in. He has a girl friend at Penn who he's been dating for almost two years. He's really really smart and gets great grades and is really charismatic and social and knows how to talk to everybody and knows everybody and knows all about everything. He flirted with me intensely for the first month and a half of college (not slutty I want to sleep with you, but telling me everything about everything and hanging out for hours everyday and everything). And then these last two weeks he's totally changed and he barely hangs out any more. He still comes to visit occasionally and will respond to texts, but I could easily let it go and see him rarely. Does he just not like me at all anymore or what? And if so, what do I do to remind him what he liked me so much for before? Hmm... ?