mixed up guy friend?

hey there. thanks for the site, it’s unbelievably useful! here’s my problem. I’m falling for one of my guy friends, I’ve had liked him since we first met but I fear my feelings towards him are growing stronger. although I felt sparks there at that time we met somehow we ended up as great friends and nothing more, and he got a girlfriend 4 months ago. his relationship has had quite a few ups and downs, and I can tell he’s still having doubts about her, but they continue to be together and seem quite happy. the thing is…though I tend to be naive about these things in this case I can tell there’s attraction between us, it’s in air, the looks and the smiles and it’s been there since we’ve known each other and the fact that I know I have a shot with him lightens me up and hurts me every single day. we spend quite a lot of time just the two of us talking and having fun. about 2 months ago I confessed to him that before his girlfriend came along I’d considered something other than a friendship with him (I didnt speak in the present though) and he confessed it had happened to him too! well, things got on quite normally since then. but there’s nothing “normal” about our relationship. he walks me home every time though he doesn’t live that close to me, buys me chocolate every now and then…I think he flirts with me and I know he cares…I don’t know what to do. then two weeks ago he told me that if his girlfriend didn’t exist he would be with me. what’s that supposed to mean? and this week he came to my house, we chatted for hours, he showed me how to play a song in the guitar (yeah, fingers touching and all) and at some point we began discussing my (non-existent) love life…he comforted me and then said that every time we talked about that he’d end up telling me the same thing…that in other circumstances he would be with me. we went silent for a while, looking at each other and avoiding each other’s gaze at the same time. it was quite uncomfortable. he also said he wasn’t sure she was the one. oh, and this same time he asked me if I liked anybody…is he completely blind? or was he testing me? I said I liked no one by the way… I swear I can’t get anything straight right now. I don’t want to suffer any more, I don’t want to interfere between him and his girlfriend but I don’t want to sit up straight and watch my heart getting broken over and over while I stay friends with him stupidly hoping that some day he’ll actually face the fact that we can’t go on like this…what does he want from me? what should I do? I can’t take him off my mind knowing what I know. and he’s too good a friend to turn my back on him because of this. all right. I’m begging for advice here! thanks…