I am in love with this guy!?

every time i see him he will stop whatever he is doing and hug me. but he has a gf.and they are VERY happy together.they will stare lovingly into her eyes and she will do the same but i know its a lie. I saw her makeing out with someone. but i know him every time i try to bring it up he gets all heated! once he even said he loved her then he kinda lowered his voice said he loved me then turned around and kissed me. I was soooo happy! but i know he is madly i love with her. I just wish i could tell him without makeing it seem like I just want him to myself. please help me!