Great stuff and letter. I can relate. My WAW for the last 6 months or so of our marriage would complain about the things that were lacking, flowers, romance, love notes, etc. I would do those things and then fade off. She shared when she left that I would do those things just so she could get close enough again, only to then have me stop doing them once she got close. So I see the logic and how the heart can harden with time.
I can say that I can't say that I felt blindsided by her dropping the bomb that she wanted to separate. A part of me had been drifting away by some of my needs not being met either. I found reasons in myself to blame her for me withdrawing (seems pretty common) and it was justified in my eyes at times too.
When my wife and I separated, I went on a full court press to win her back and while it worked initially, a wise female told me that it was actually doing more damage because those were the things she wanted all along.
In many ways, I tried harder when I lost her and I could see how females can look at it as a game. Gaining that trust back and willingness to give it a chance unfortunately won't happen until she is ready no matter what we do. The more we push, the faster they run. It hurts like hell because even detached, most of us LBS want nothing more for reconciliation.