My "ex boyfriend" and I still talk regularly, and he seems to think it is okay to tell me he loves me and to act like he wants me back and then change his mind within the next couple hours or the next day. He sounds exactly like you in the aspect that he was super busy with classes/work ALL the time and apparently that is why we broke up in the first place.

So, my advice to you would be to back off and give the both of you space to let each other go. Keeping contact only keeps the flame burning, in my opinion. But I'm a bit of a hyprocrit because I tell myself the same damn thing and here I am, still talking to the dork. Love is too complicated!