PLEASE HELP–ADVICE????

Hello,
I am 26 years old and have been dating the same guy for a while. I love the guy I am with, but have been talking to another guy (I will call him second guy) online for the past three years (which makes things complicated because i know I need to pick one). I have great relationships with both guys, but I know the second guy is not ready for a commitment. I have been intimate with the second guy, and we literally talk on the computer every day (or we text silly things). We have such strong attraction (mentally and physically) and its confusing because I know he is going to be moving away for school and knows he cannot enter into a serious relationship. I recently broke up with my boyfriend, and wondered why the second guy backed away (I figured he would jump all over that when I became single)…i took it personal at first. I just recently confronted him about it (because I know how much he adores me—we have everything in common and we are very attracted to one another). After confronting him, he said that he fears getting close to me, because he knows it will lead to commitment and he can’t be in a serious relationship right now (because he is going away). This is nothing new….i knew he felt this way about getting into a serious relationship for a while. He has told me about this commitment/serious relationship fear for a while. He sort of acts like, if he had taken it to the next level, that he may lose me….and thats a huge risk. He recently started “seeing” a girl that lives in another state 15 hours away….when I asked him why he didnt take that initiative with me…he said that he had nothing to lose with this other girl….and if it ends it just ends —no strings attached. I told him that I would have understood if that had happened to us…and he did not agree. We both know we could have something awesome….but there is something he fears with me. You would think that if someone has a strong attraction like we do (physically and mentally) that they would go to any lengths to be with you…but he has a fear that I cant figure out. It is almost like he loves talking online and texting because he knows its safe….and when we get too close— he gets scared. My question is—– how can this guy be perfect for me—-but in many ways be scared to get close to me….can he actually be afraid to commit to me incase he loses what we have when he leaves? At this point —I am back together with my boyfriend—- but I question why he didnt take the plunge if we are perfect for each other (and we both know it). Please advice? Now that I am back with my boyfriend…I feel like he is relieved that the fear to get close to me doesn’t have to be there—because I am in a relationship (now there is no risk that we could get too close). I have asked him if we lived in the same city if he would be with me…and he has said he would find it hard not to be (although he fears this….. the distance keeps the fear in check). Advice?