1) Angst/Guilt: he knows he's being unfair (in terms of not bringing much to the relationship) but he's not really able to do more (either he can't or he won't)
2) Emotional Ambiguity: My question to you is: what does it take to get an INTx out of the gray area?
Maybe time, maybe nothing will. Not something you can really do anything about, has to come from him.
(I've never yet been able to conquer it in myself)
3) Random Intervals/Lack of Pre-Planning: Any advice about his lack of pre-planning? Is this an INTx trait or does he lack the courage to tell me he just doesn't feel strongly enough about me to pre-plan?
Certainly an INTP (more than J) trait. It needn't bear any relation to strength of feelings, we just don't really do planning. If this is a big problem for you you shouldn't be with one because they'll drive you crazy. ENFPs don't usually get too uptight about that kind of thing.
it hurts like hell when he withdraws, but i recently told him (when he expressed regret over not being able to be more of a constant in my life) that i have decided that his inability to spend more time with me has less to do with me, than it has to do with him and things he's struggling with. his reply? "Exactly." i totally trusted my instinct on that one, and was amazed at how quickly he was to agree with that statement.
can any of you INTx's relate to his reply?
Sure.
Don't expect it to change though.
I don't really understand the "hurts like hell" comment, coupled with your supposed understanding that it has nothing to do with you, and I doubt he will ever be able to do so either.
You'll end up guilting him about something that is as natural as breathing for him (in fact, you've already started the process). He'll end up resenting you for being needy and unreasonable. You'll both be miserable and you'll break up.
INTs are a bad bet.