I am told I should be kind, be loving, treat her as if we were very best friends (but not be needy/grabby).
At the same time, in reading on infidelity and EAs, I'm reading where the wayward wife gets some of what they need from each man, and so she has no need to change.
If I do not have sufficient proof of an affair, and I act like her best friend, w.t.f. WOULD she change? She gets the best of both worlds.
The idea is that once she's asked the question "would the other guy make me happier over the long run?", she can't really unask it or put it out of her mind; she won't be able to put the matter to rest until the question is answered. Because of the lack of morals needed to pursue a relationship with a married woman, the answer to that question tends to be "no", and the straying partner will be more motivated to work on the marriage after she learns that answer. Being a happier, stronger, more friendly version of yourself throughout ups the changes of that answer being "no". Being a clingy, whiny, over-controlling version of yourself drastically reduces the changes of that answer being "no".
Of course I haven't seen Nop's overall strategy, so I'm not sure how it compares, and I've never been in that position personally (knocks on desk that looks like wood and might even be wood...)
a fine and enviable madness, this delusion that all questions have answers, and nothing is beyond the reach of a strong left arm.