Your situation is classic textbook walk away wife.
She's not having an MLC.
She's not having an affair.
She's simply reached a point where things in life are such that she feels capable of ending a marriage that has been unfulfilling to her for far too long.
Don't get in to playing word games with others on here who will try to convince you to kick her butt out the door.
Everything in those books applies PERFECTLY to your situation.
For crying out loud, you've already carried out MUCH of what is in those books as suggestions for restoring your marriage.
Things are good, not bad.
Honestly, if this thing fails, it will because you grew impatient and quit.
Blessings,
Bill
"Don't tell me the sky is the limit when there are footprints on the moon."