Whats his deal?

I share an apartment with my guy friend who i have known for almost 2 years , Anyways i have always thought he was cute but neva really thought about liking him more than a friend . Well lately i have been starting to feel something for him and i think he does too but its hard to tell if he is just being a friend or more. Well lately i have notice that when i talk about another guy or if a guy talks to me he seems to get alittle upset or if i talk about a guy . He'll talk about a girl and she was hott...whats his deal?