My friend is avoiding me, or "too busy". Should I just not try anymore?

Well, my friend and I liked each other. But then he had to go away for college, so we said we'd be friends and keep in contact through AIM and texts. Well now he never gets back to me or anything. I brought it up to him several times, but he says he's busy. However, I have a friend who has twice the workload he does, and manages to speak to me at least once a week. I'm not asking for a full conversation, just a nice "hello" or "how are you doing?" Should I just not even try anymore, because it hurts a little that he doesn't even try like he used to?