why?

I wonder why I've ben getting upset so much lately at my bf, I mean he has not done anything wrong. He never asks about my day or how I am feeling anymore, I don't know where I went wrong? He clams he's been busy with work and school and I talk to him once a day, literally one text because he won't answer until the next day. Usually on Fridays he will talk longer but like at 11 or 12 at night, its a long distance relationship, he's an hour behind. But I had a ****** week and was tired and I fell asleep and I didn't get to talk to him, I felt so awful and i cried for a very long time, because I had ruined our time to actually talk with each other for another week. I told him I was sorry repeatedly and he said it was okay, but I don't believe him, he's mad at me for falling sleep on him. Even though he falls asleep on me all the damn time but I just feel awful that I did. I texted him once yesterday and he actually texted back a few times, but I still have not answered him. why? I don't really know. I do want to talk to him but I know he's not going to answer me back. I honestly don't know what I did wrong.