Does he like me? Or is it my imagination? :)?

I like this guy, lets call him Bob. I have him for one of my classes and i sit behind him. I have known him since middle school and were now juniors in high school. I thought he liked me back in Middle school since he always wanted my attention and would always tell me you are so smart you should be on this, but I would blow him off since i had really low self esteem at the time.

Now he is always nice to me, and he always asks me if im okay if i hit myself by accident. He always asks me for help with homework, and he tries to help me out to. We dont talk to each other outside of class, but he also initiates friendly conversation with eye contact.

Such an example: Hell ask me how my day was, and hell mention things i did not even know he knew about me, for example why did i stop hanging out with my friends to be with some different ones. Hes tried to help me in work but failed miserably and he was pretty embarrassed. He always faces me when talking and smiles at me, and gets in my personal space. When we were alone he would just initiate random conversations with me, and but always something about me. There are other smarter people around him that could help him, but why does he always ask me for it, and why is he so nice to me while he can be judgmental about other girls. Its so awkward when he asks me for help since well always make eye contact and i look away. But when i look up he always seems to pay attention to what i have to say and when i look up he looks down.

I forgot to mention he has a girlfriend, so i know i wont ruin its just for plain old curiosity, im not a home wrecker, plus i do like him and dont want to look like an idiot.

He always teased me in middle school and has always been nice to me, so i dont know. I guess im over reading this. He never mentions his girlfriend, shes in college