I think he totally forgot about me. What gives?

He's out away with friends. We message all day every day. I've been going away a lot too and I always make time for him. He on the other hand left me high and dry. I feel ridiculous for messaging him when I should have been paying attention to those around me. He hasn't returned this action to me, evidently. Thing is, I've been real with him. I can't just not respond to him next time I'm busy. He's actually left my messages until the next day. And he doesn't have reason for it. I think he's just doing it to do it..