I would want to know but I would want to be told nicely
If I were the "cheated on" spouse I would want to know.
However I would want to know nicely.
I love the op who said she would take folks out to coffie and let them both know what is going on around them.
I have been told before about both my late and my current guys. I usully say thank you and let the conversation drop no matter how close a friend that tells me. Even when I show no emotional response to the friend I follow up. If I need to.
While I do get information from others and listen politely ultimatum the relationships are at home.
Difference between poly and cheeting.
If one of the partner doesn't know because it would hurt them, hurt you or mess up your life. Its cheating. Consent without converse/coercion equals an equal relationship.