Hi Sam - I dropped into your thread, as communication with OP was a big deal in my situation (now vastly improved). Sounds like your W is v confused - she is seeming cold and distant from you - but hasnt taken the step of leaving - despite the Big Speech.
Remember, confusion is good. Backing off and patience is good - but I also agree that having done the Dobson letter - you need to hold firm. Was v surprised that you said you had both read the book - maybe that is part of problem? She thinks you have applied a formula? I kept the book well hidden from H - seemed to me important he didnt think I was just doing something someone in a book told me to do!
She is floating: yes, fantasy A means their R is always perfect. But you are there, flesh and blood. Is it possible she may be 'missing' that you are not being rather more emphatic about your needs in the M? This isnt saying she has to do this or that to make you happy, but being clear about what your objectives are. as per Dobson.
I have to say, after I stated clearly to my H I would not be in a M with infidelity (& he instantly ended his A - tho not communicating with her at first) I asked myself whether I had ever actually stated the obvious, and said, I did not accept his adulterous behaviour as appropriate in our M.
And if I didnt state that, was it not perhaps understandable that he continued his A? Is it possible your W, in her confusion, actually isnt that clear about what YOU want, and thinks she can get her emotional stuff from the A, and the security and stability you offer. She has to realise the latter is dependent upon her full engagement with you for the former.