I think your read on the book is dead on. My WW bought a couple as well. Never even cracked them open. It was her way of easing her conscience. So she could say later, I even bought blah blah blah books. Keep DBing.
Agreed and that just reminded me, when my XW finally left the house she cleaned out her side of the closet including all of her books. I had found DB'ing by then and had secretly read DR while keeping it hidden in my briefcase in the car. So imagine my surprise when I saw the cleared-out closet and she had left behind one book- her own copy of DR. Wow what a kick to the groin that was! I have no idea how long before that she had bought it. Crazy.