You seem to be confusing acceptance with approval. Acceptance simply means you acknowledge reality for what it is--reality. You don't have to like it, you don't have to put up with it, but it still is.
From my experience, the reason acceptance is so difficult is because if you truly accept reality for what it is, then you often realize you can't go on the way you are. If you were to accept your situation for what it is, and accept that you are powerless to change him, you would likely have to make some changes yourself. And that appears to be what you want to avoid. (It was the same for me, I refused to do anything until the pain of it all brought me to my knees.)
L