Well in my H's case I think it's because he KNOWS that it will be painful to face many of his demons and do the real work that would need to be done, and he's an avoider to the nth degree. Also for him, actually adressing those demons would (for him) be tantamount to admitting fault (ie I'm right, you're wrong)...and he will resist that equally as hard. His admitting there is REALLY something deep down that needs to be addressed would be like him saying "you were right".
While I'm NOT out to say "see I'm right, you have stuff that needs to be worked on...", in his mind it would be the equivalent of losing the fight. KWIM?