Same story happened to the great Casanova while he was in London (princess girl who took all his money with no sex)
He mostly committed suicide ... and finally surprised her fucking some random delivery men.
So here we are, few solutions
1) Ask a friend to fuck her, that will destroy the image she built in your mind
2) save your couple, by having someone fucking your wife once, better if you are watching
3) Read the memories of Casanova