Like one who grabs a stray dog by the ears
    is someone who rushes into a quarrel not their own.

-Proverbs 26:17, NIV

Cheaters manipulate others to do their bidding.

They can use the genuine, good desire of others to “help” against them and against the faithful spouse. Cheaters feed these “helpers” only certain information and then release them to work on the faithful spouse.

This might mean telling them about marriage issues as they see them but ensuring no word of their cheating is included. The point is to put all the blame focus upon the faithful spouse for marriage trouble. Some “helpers” are all to eager to fall prey to this manipulation.

When the cheating comes to light, these individuals have a choice to make:

Do they apologize to the faithful spouse and admit that they were used?

Or do they double down in denial and claim they were always pursuing “legitimate” issues?

In my experience, these individuals usually choose the later and thereby find the relationship terminated by me, the faithful spouse, as these individuals are unhealthy people who are choosing to live in denial of reality.