Perhaps he did/does like you but you don't give him much feedback to let him know you reciprocate. If he feels like its pointless trying to pursue you in his subtle ways, he maybe finding a new interest.
Perhaps you should ask him to hang out or study. From there, the two of you will get more comfortable with eachother to be open and communicate more efficiently. I see that both of you are incredibly shy toward one another. Time to break the ice, Sweet Pea. If something sparks, great; if it doesn't, you will at least have found a good friend.