And he said, That which cometh out of the man, that defileth the man. For from within, out of the heart of men, proceed evil thoughts, adulteries, fornications, murders, Thefts, covetousness, wickedness, deceit, lasciviousness, an evil eye, blasphemy, pride, foolishness: All these evil things come from within, and defile the man. – Mark 7:20-23, KJV, (emphasis mine)
When marriages dissolve or adultery is discovered well-meaning pastors (and counselors) often will give the advice that the faithful spouse must “own their part.” This is incredibly unhelpful and painful advice to hear following soul rape and the emotional/spiritual dismemberment that comes with divorce. It is salt to the gaping wounds.
What makes this advice so deadly is how it hooks into a little truth to make it difficult to dismiss. Satan and the demonic world is most destructive, after all, when they mix in a little truth with the lie.
No one is without sin (Romans 3:23).
So, that means every marriage has sin within it. This includes “good” marriages as well as difficult marriages. No one is except from the consequences of original sin.
We all have places where we need to grow in our sanctification (see I John 1:8).
It is a pastoral error to confuse this need for spiritual growth as a cause for the adulterous decisions of one partner. Plenty of marriages share the same issues as marriages ravaged by infidelities. However, the spouses in those marriages chose to remain faithful despite similar circumstances.
The difference between those marriages lies in the heart of the adulterous sinner. They chose to give into temptation. Only they are capable of choosing otherwise and repenting. As long as they continue to blame the other spouse and/or the marriage, they are not repenting and are stuck in their sins.
Blaming the faithful spouse–in that sense–is a further pastoral error as it does not help the adulterous spouse truly repent.
That said, I do encourage faithful spouses to grow and mature. Repenting of our sins is needed for the rest of our lives as no one is perfect except Jesus. But it needs to be crystal clear this growth and repentance has absolutely no causal link to the adultery or abandonment by the cheater.
Faithful spouses ought to always reject accepting any sort of blame for the infidelity of their (former) spouses.
Personal growth is good. Investing in the person that you want to become is a good investment. Accepting blame for something done against you and God is not good. It is ungodly. And any counsel that says otherwise does not come from the heart of God.