It's common advice, and very flawed.
An affair left secret constitutes lying by omission, every single moment of every single minute of every single hour of every single day of every single year.
The secrets and lies erect an impenetrable barrier to the emotional intimacy necessary for a healthy marriage.
Trust me on this. My husband kept an affair secret for over a dozen years. Did I suspect? Yes. But ultimately, I let it go---things were "good." Only we never--not once, not fleetingly, NEVER---again experienced anything resembling closeness in our marriage. (Obviously, my barometer of what was "good" changed dramatically. It changed as I started believing the subtle messages about ME, and the shortcomings that made this man so miserable.)
(About a dozen and a half years later, it was confirmed that he is personality disordered and not really capable of true intimacy; even so, the difference pre- and post- infidelity secrets was astonishing. And decimating.)
I spent those intervening years wondering what was wrong with me---what had changed in me that made it so onerous to spend time with me, talk to me, be with me, have sex with me.
The real issue is that there were secrets and lies between us.
And those secrets and lies were more important than me, our marriage, our family.
I never learned what those secrets were, except very superficially. There is no way I could have ever established a genuine, intimate marriage again (assuming he was capable, which it turns out, he was not).
And I don't think anyone ---regardless of his/her spouse's mental wellness---can re-establish emotional intimacy when there are still lies and secrets.
[This message edited by solus sto at 11:08 AM, August 7th (Wednesday)]