How to get over best guy friend who you meet everyday?

Hi! I'm new to this site but I really feel like I need to get this off my chest. About two years ago I started in a new school (high school) and I met new friends there. I got especially close with one girl and one guy and we kind of made a trio. However, an odd number of people is never good and it often turns out that one is feeling a bit left out. Lately, I feel as if I'm that person. The thing is that my "girl-friend" is very smart and my "boy-friend" hangs out a lot with her during classes and they do assignments together as I'm not as quick/smart as they are. And that's when I feel left out. They get so absorbed in their things and have fun together while I'm just sitting beside, getting sad and quiet. I sometimes try to get contact but they won't listen or they ignore me (I believe unintentionally), and this makes me so frustrated that I often go to other friends in the class and do the assignments with them so that I won't feel alone. I've had a crush on the "boy-friend" for a very long time, and I think my "girl-friend" is in love with him as well. He, however, does not seem very interested in either of us, or equally interested. For sometimes he is a lot with me, other times a lot with her. He has nicknames for us, touches both of us in a friendly way, and teases us. He and I share pretty much the same kind of humour in one way, and he and she in another. My "girl-friend" and I are very different people but I really like her as she is kind, caring and funny. I haven't told her that I like him because I don't want to start some love triangle, plus she would probably tell him anyway and I'm afraid he will just say "I don't see her in that way" and I would just feel humiliated. I'm very insecure so I don't want to get turned down. I just want to get over him, as I see that things are getting impossible. If he and I get together, against the odds, it would probably hurt my girl-friend and if he and she got together, I know that it would be devastating to me. If I stopped being so attached to him, maybe I could get over the two of them being so close. I don't know many other males that well and he has really gotten to me in a way no other man has before. This crush goes deeper than the shallow ones you sometimes have on people you don't know. What am I supposed to do? I want him so badly but I want to get over him at the same time because I don't want to ruin our friendship... And I see him everyday at school so I can't even avoid him.

I'd be very, very thankful if someone could give me some advice!!

As a relationship seems like a fairly low chance (one of you needs to make a move for it to happen!) then you can only address this as you would if were a normal friend situation and you were feeling left out.

I'd start by telling your friends (when they are together) that sometimes when they are engrossed together you feel very left out. If they know you're feeling this way, they may well alter their behaviour to include you. Alternately you could join another group. Or perhaps a there are people who would be happy to hang out with you and the other two and then 3 will no longer be a crowd.