I hear what your saying. Sometimes you wonder if they will ever get it. How approachable is your B? How has he been involved so far? I find myself, even though things seem to be improving, wondering why I want to risk the same problem again. Like you, even though W is starting to change, she hasn't made the effort to convince me that it won't happen again. So even though we seem to be headed in a better direction, I'm not sure if I'm convinced.
I've decided I better go talk to the B, hopefully either he or a C will help me get past this stumbling block. Perhaps what I'm saying is maybe there needs to be a third party involved, that will drive some positive change. That's the path I'm leaning towards.