Completely understand how you feel. I find it easier to detach and to work on my leaving plan whilst he is being an a-hole. But when he's not - well....how do you keep up your resolve? I find it hard. My AH is currently on a wave of nice too...and it makes me sad because I remember what about him it was that I feel in love with...but I also know I am being manipulated, and that also, from past experience, it wont last.
I've considered making a list of all the specific things that he's done that has made me want to leave so I can review it in times like these....but that seems so bitter and negative....