I text him every day, and he only answers occasionally. He seldom calls me and always says he is busy, but he will call me in a day or two if I ignore him.

Judging from your description, at least now you care about you more than he does. Maybe he likes you but not to the point where you have to, or this lukewarm state will not appear. Even if a person is busy, he will take the time to tell the other person about the day or send a short message to tell the other person what I am doing, so that he will not worry that this is the minimum way of communication, not this vague and perfunctory practice, and he cannot use work as an excuse for his behavior. You'd better discuss it with him! Face to face, maybe the problem will be solved. Please cherish each other if you have feelings!