Thou shalt not commit adultery.
-Exodus 20:14, KJV
Christians need not dig very deep to figure out what went wrong in a marriage when adultery occurred.
Modern psychology and so called “Christian” counseling might disagree with me. However, I am very adamant that we do not treat adultery as a side issue to a marriage’s demise.
Why? God takes adultery seriously (see The Ten Commandments).
A truly Christian approach requires a pastor to treat adultery as always wrong and always potentially marriage ending even if in only one instance (see Ex 20:14, Deut 22:22, Mt 19:9, etc.)
Breaking of this fundamental moral code–namely not committing adultery–is what went wrong in a marriage to a cheater. It is that simple.
If the cheater wants to explore the darkness in her heart (see Mark 7:21-23), they can dig there, too. Blaming the faithful spouse or the marriage is out of bounds in such discussions. The only hope for the cheater’s soul is for her to face her sin, take responsibility, and turn from it.
Question: What went wrong?
Simple Answer: One spouse chose adultery over honoring God and their marriage vows.
It really is that simple. God doesn’t allow for any caveats. There’s no need for a forensic examination of the marriage, family of origin, etc. He forbids it upon pain of righteous judgement from Him. To proceed anyway is a deliberate act of contempt for God and and a direct challenge to His authority.
After 13 years of marriage, my wife while visiting her sister in WA. State, meets a married military man, begins a romance with him during her week longstay and 6 weeks later he comes to town to spend the weekend in a hotel with her, all the while I am told she is on a business trip. They meet throughout the year to spend a weekend or week together while I am told she is caring for her sick sister. It lasts 3 1/2 years both physically and emotionally before he dumps he for his new side piece. Fast forward 25 years after countless hours of counseling and reconciliation, and I find a birthday card written to him on her desk. I realize this is her trying to reconnect after all these years. I am devastated and trust is forever gone. Its been 5 more years of counseling and reconciliation because I love this woman and am willing to try to make things work. She gas lighted and rug swept the whole affair until I produced the evidence I have collected from the first affair and she finally admits it was sexual and emotional. She believed he would divorce his wife and marry her the first time around, and told me “she was not longer in love with me”. This time she tells me, “he just popped up on my mind because it was his birthday.” I married until death do us part, but a part of me tells me that death can be interpreted as the death of the marriage as well as physical death. Am I wrong.
My take is God gives us permission to divorce an adulterous partner (see Mt 19:9). The marriage was over in the OT per the death penalty (see Deut. 22:22). Divorce is a merciful alternative today.