Hi Steph, You mention that you feel things have gone downhill ... from my POV it looks like you have just levelled off again at a slightly higher plateau, but your W's basic stance has not change so she will continue to resist anything that threatens those beliefs and will express in absolutes (No chance, no way, no how, etc...) in order to re-affirm her resistance, but internally she is struggling to keep her resolve inspite noticable recent changes for the better.
I know you really don't like the idea, but I tend to agree with the others about backing off spending as much time with her. You know how much she likes the time you spend together and it has worked to a certain point but is not enough to change her beliefs yet. Time to try something different ... the ole cliche "Absence makes the heart grow fonder." So perhaps its time to give her what she asks for. Demonstrate to her that while you may prefer to be with her, you are just as content spending time without her.
I'm suggesting this based on my own experience. While like you, I continue to express that I believed the M was not over yet and as long I believed such I would to fight for it (without persuing mind you), however, I also expressed that there would be a limit to what I would be patient with and therefore there was a danger she may cross a line where I would determine the M was not worth saving and there would be a point of no return. While I was uncertain at first where that limit was, I did work on demonstrating that I no longer needed to be with her to enjoy my time and if she didn't want me around, then I would rather be doing my own thing. Even today, when we are back in a "saved" M, when she seems to get indifferent about me being around, I'll go off and make myself scarce (sometime taking D along too.) When I come back, she always changes her mood and lets me know she wants me to be around her.