I do remember reading that one. I think the idea of trying to remain as your spouse's friend is a good idea, at least in theory.
However, I am in a bit of a Catch-22 paradox with my W. I know full well what a friend, a true friend, would say and do around W. A true friend would never let her get away with half the crap she pulls.
My W, however, does not want me as her friend in any way, shape or fashion -- she only wants people to approve of and affirm her wrongheaded ways. She wants me to kiss her butt. Or to roll-over and give her any absurd thing she wants.
But while being that sort of "friend" might make her feel less hostile towards me, possibly even friendly, she would never respect me -- and that is the other serious issue between us. And without respect, our M would still be impossible.