And the Lord God commanded the man, “You are free to eat from any tree in the garden; but you must not eat from the tree of the knowledge of good and evil, for when you eat from it you will certainly die.”
-Genesis 2:16-17, NIV
I suspect many of our cheaters were addicted to the “high” of partaking in “forbidden fruit.”
It is a childish fetish. The cheater goes for what they are not “allowed” to have. Such partaking gives them a thrill, a high.
Maybe your cheater was always the type who flirted with the line of acceptable and unacceptable behavior in the marriage?
It is like some cheaters were teenagers who are late to the rebellion stage. What they should have worked through in adolescence is now suddenly a problem for the faithful spouse.
They might claim to be sophisticated and all that. Yet the reality is that they are behaving like entitled brats who never really learned self-regulation and self-control.
Rather, they want to partake in the “forbidden fruit.” Such is as old as the Garden of Eden. It happened back then and continues to this day.
My wife is very much stuck in some period of her childhood. As a consequence, she’s emotionally stunted from years of parental abuse and rejection. Not an excuse at all, but there’s a reason Paul commanded Christians to renew their minds in Romans 12:2. Her’s is still looking for the acceptance and validation she never received from her earthly father and mother.