I'm confused...do guys talk and behave this way with girls, even if they are just friends???

So I met a guy 2yrs ago, and we have become really good friends. 1yr ago, I started liking him, a LOT. I think he may have caught on, but we kept it platonic (tho he tended to tease/flirt often), since he had a gf he loved. We just studied & talked a LOT. 2months ago, the gf broke up with him. Well, my friend (against my choice) asked him the day after if he liked me, and he paused a while & said as a friend & kept asking her if i was mad. Following month, we chat lots (4+hrs). Grew SO close. After break, I go back to school and he is blushing around me, staring nonstop, and I get home and he texts me TONS w/ questions i know he knows the answers to. He calls me 2x, just to talk (w/ that flirty voice). He teases me in cl, by calling me and smiling from across the room. Gets home, texts me, and then we chat online again. But we never actually talk at school THAT much, cause of mutual friends :\ What is going on? I thought he said he only liked me as a friend?!!?