I think you should write everything that makes you afraid of being in a relationship with him. Then I think you should read over it and show him. Then I think you need to discuss what you wrote down with him over a few days.

Your breakups sound like insecurity.

I don't know if doing something like this would cause a permanent break-up, but I did something like this and it helped my relationship.

I think you should ask him to do the same thing. You'll probably end up hurt by some of the things he says, but he'll probably be hurt by some of the things you said. However, it can help you compromise and discover whether or not you guys are really compatible long-term since it would require both of you to make some behavioral changes to compromise for one another's happiness in the relationship.

But mostly, you sound insecure.