You seem like a great guy man. Been reading through your sitch.
I agree its probably not productive to think about why W is doing what shes doing. Every time I do it in my sitch it throws me into a rabbit hole that never leads anywhere but feeling depressed.
My wife also left after two years. Its a tough thing to understand. I think thats where it helps realizing we may never know why but accepting whats happened and realizing we can only control ourselves. ( This is also advice for myself because I'm struggling with all of it.)