Choc, what kind of person is your W? Is she a Christian? Impeccable morals? Active in your church community? Loves her children? etc...
Burg,
Yes, my wife is a Christian. Before we were married, we went to Bible study together, we never had premarital sex (OK, we did go pretty far, but ...) and she's always been, by all accounts, a very moral, upstanding woman. She doesn't consider herself particularly "religious," but it's been HER over the 20+ years of our marrage, I'm ashamed to say, who has gotten us back on track when we hadn't been praying as we should, or going to church as a family.
That all changed when she had her affair. Suddenly, she didn't want to "talk about God" anymore, and she got EXTREMELY defensive when I would invoke God in a conversation about her behavior.
Simply put, Burg, since the two couldn't co-exist in her moral framework, she altered her beliefs, to fit her desire (her affair), rather than try to justify the affair in the context of her beliefs.