What's with him/ what's his problem?

k I've known this guy for 6yrs this year he asked me out, I turned him down, he asked me out again a week later, I turned him down again only a month after that I realized I actually like him. He's kinda a flirt but he's really funny and a really nice guy, I sit next to him in band and he's always making jokes not directly talking to me but always side glancing me to see if I'm laughing or smiling he asked me out last month again this time I said yes but we still haven't gone out, and from his reaction when I said yes he wasn't expecting it, we barely talk, and when we got pics taken two weeks ago for band and choir, choir went first (he's in both groups) and for the funny pic for choir he took the girl that was standing next to him and dipped her back and made it look like he was kissing her. He's in one of my other classes and keeps walking right in front of my desk and talks to my friend next to me but kinda looks at me while he's talking to her. Lately I've been talking to another guy(call him phil) and he's seen me talking to phil (I don't particularly like phil) and since then he doesn't look at me, doesn't say anything and earlier this week I saw him and he had a very peeved look on his face about. I gave him a small smile the other day I passed him in the hall but he wouldn't even look at me. So does this mean he's jealous or has he just been messing with me all along?