If you really wanna be with him, then back off and give him space and time to sort his head out.
If you're feeling the strain, and no matter how many times you've tried it just doesn't seem to work, then get out now.
At the end of the day, advice is good, but its easy for others to tell you what to do when they aren't the people dealing with it. I would have kept plodding on had it not been for a good hard kick up the backside from a good friend. Its not easy, and yeah I'll admit that I miss her company. But life goes on, and I've just met a great girl (who has a lot more in common with me!) so all is good.
Don't be too available - he sounds like a *beep* to me. How much of what is in his head actually real? I dont know you or him, so i may be off the mark here, but its not unkown for people to over-dramatise things to win affection! Especially insecure people. Either he wants to be with you or he doesnt. You only get one life, so don't waste any of it!