Like I said, it depends on whether saving the M is the goal.
No, it doesn't. That discounts the thousands of marriages that have been saved by this technique. I understand it's in the minority, but it's probably a 40/60 minority, and best-selling books and counseling practices have been built around it.
It doesn't depend on whether saving the marriage is the goal. It depends on whether or not you believe that exposing an affair will hasten its demise, or whether you feel it will do more harm than good. It's a valid technique, whether you agree with it or not.
