Puppy, please - tell me what works. I'm reading "Not Just Friends" right now, hoping for some insight, but with Retro hanging over our heads, I feel like there's a need to cram.
To me, what works is a combination of the two approaches -- the Dobson, MarriageBuilders "tough love" approach and the more passive, forgiving, "While They Wait" approach espouses by MWD.
I think you aggressively attack an affair, thru a CAREFUL PLAN of confrontation and exposure (after getting iron-clad proof), and, if necessary, a hardball legal stand. All the while working on yourself, GALing, making yourself the better option. What I call "shining a light back toward your marriage."
It is rare that I've ever seen totally one approach or the other work -- I think you have to combine the two.