Yes, I did call out a friend who was talking to a M man years ago. Told her karma was a bitch and to put herself in his W's place and decide if it would be ok with her if her H was "talking" to another woman.
Another friend came to me when he reconnected with the "love of his life" on FB and was thinking about leaving his W. I told him that he made the commitment to his W and that includes doing everything possible to work on that R. If they couldn't work out their problems then D and see if the old flame is really his soulmate. He thanked me for the advice and resolved to have the difficult discussion with his W. We haven't talked about it since because it would be inappropriate so I don't know how it went. But it was almost a year ago and I know he is still with his W.
If you love somebody, set them free. http://tinyurl.com/2empx2g