I don't know your whole story, but the whole "runs away then comes back" thing is always a bad sign to me.

Have you done marriage counseling yet? It's worth a try, even if you can't get him to go.

It's possible that the situation is just more than he can handle. Just remember that it's not your fault...you didn't ask to be bipolar, and his limitations are his responsibility.

Does he provide stability in your life? Do you think your life would be more stable if you were on your own?