Mrs. NOP, I think your reasoning is sound, as usual, but my point about Mrs. ZB declaring herself to be a bad lover was NOT about her feelings but about her definition of herself and what actions might fit within that definition. It's the way some people say they can't cook, they are no good with computers, they hate math, they can't sew. People who make those declarations are also saying, don't ask me to cook, fix the computer, solve for 'x' in this equation, or hem this dress.
If this were a brand new story, I'd say to send ZB off with instructions to accept his W's feelings, BUT also make clear requests about what he wants her to DO, and then report back.
It's my understanding that ZB has alread made those requests and W has turned him down. She turns him down with the "excuse" that she's a bad lover, but my point is that she has no desire to be a good lover no matter how or how many times he asks her. And if you follow that up with, "She's being extremely selfish and inconsiderate in refusing to do even a simple action to show her love for ZB," I think everyone here would say that's exactly right.
Again, it's like someone saying, "You're such a good cook and I'm such a bad cook... AND I like never having to cook and knowing that you will never expect me to cook because I have made it clear that cooking is not something I ever want to put on my resume."