If you can't go through a long distance relationship again, and you have to join the army, then you have to break up with her. If you can't go through a long distance relationship, and you can't be without this girl, then you cannot join the army. I think, however, that if you want it badly enough you can do the long distance thing. Love triumphs over all. If you are in love, and you really have to go away, then you will be able to stay together. Just keep your head together while you are away and for god's sake don't cheat on her.