Why is he acting this way? Does he have feelings for me?

One of my closest guy friends has been acting a little differently and I’m not sure how I feel about him. All of a sudden I find myself wanting to talk to him whether it be online or in class all the time and I smile whenever I see him walk in the door because I know he’s gonna make me laugh throughout the class and brighten my day. He is a flirt, but now its gotten a little more than just “friendly flirting” you could say. I’ve known him since 7th grade and we’ve been in at least one class together every year since freshman year of HS (were seniors now). He always makes fun of me and jokes around with me, some people may take that as flirting. last year, even our teacher noticed and asked our other friend if we were going out! (we weren’t and never have) he sits right behind me in class this year and will sometimes play with my hair. And a few days ago when he was absent, my teacher asked if I knew he where he was, when I said I didn’t know (I did know,he was at a v-ball tournament, I just said the easiest answer) another friend who sits right next to us joked “why not isn’t he your boyfriend?” I’m starting to worry that people think its me trying to get him and flirting with him but its not. He’s the one with the girlfriend and doing these things! we both play volleyball and he wants me to go to every one of his games. I missed one home game last week and I had to make him brownies so he would forgive me and he now expects me at every home game to watch him play (I’ve only seen his girlfriend at one of his games and it was last year btw). We are always partners for projects. Last year, us and our other friend had to make a music video for a project and we did it to “love story” by Taylor swift. I was “Juliet” and he was “Romeo” in the video. Then this year, he left me a voice mail on my phone at 1am and he was singing the song! He had no idea what the lyrics were but he was saying “I am Romeo and you are Juliet” over and over and “its a love story baby just say yes”. when it came up a few days ago, at first he claimed it was his friend singing but then when it was brought up again a couple days later, he didn’t deny doing it and joked that it was “irrelevant to what we were talking about” Him and his girlfriend have been going out for awhile, last year when they started dating we all thought he had had a girlfriend just so he could have a girlfriend but there still together and on face book there “engaged” and theres a bunch of pics of them together. why would he do all this and act the way he is if he has a girlfriend???

One more thing: he asked me to ask our another friend if she thought he was hot, when I asked why he said “ I like to know these things” and he jokes around saying hook me up with your little sister. Sooo confusing. My friend thinks he likes me, she says the way he talks and acts with me and his girlfriend are completely different. I would never ever do anything to break up there relationship.

what do you think? sorry this is so long but I’m just confused and not sure if its just innocent friend stuff or something more.