He seems to be a confused person. He may want one thing, but to make it reality is a totally different thing.
I went through a time where I wanted commitment and when it came to me, I was so scared that I ran away. So I completely understand where he is coming from. Howevever it doesn't make it right that he doesn't provide you a reason for his actions. Obviously he is not man enough to talk to you about his issues, instead he just runs in the opposite direction. He may want to give you everything you desire but his inability to do so may make him feel like a loser/failure which could be another reason he is not contacting you as often.
You need to give him his space, don't get in touch with him at all. Let him know what life is like without you. Move on in the meantime and find someone who is worthy of your time, who will be man enough to commit to you and make your happiness his priority. You don't want to marry a man who runs away from his problems. Communication is vital to a good relationship.