Long distance relationship

My boyfriend and I know each like 5 years. We've been together for a year before (also long distance) but we saw each other a few times. We're back together for almost 3 months again and there is almost no communication between us. He says he is always busy working and that I understand completely but when he has time to talk he doesn't. Sometimes we have a conversation once a week but that rarely happens, sometimes we never speak at all! I really love him and he says he loves me more than I know and that there is no one else he wants he even asked me to marry him! But with this long distance between us it's hard to have a relationship when we don't see each other. I don't know what to do??? Should I keep trying or should I just end it with him?? Any suggestions???