If you can see a serious impending problem in someone else's life, shut up.
If your friend is about to marry a con artist, your good friend’s wife is cheating on him or a teenager you know is having unprotected sex, keep your mouth shut.
The first story is one that I learned about. A good friend of mine, with whom I commuted daily to graduate school, became engaged to a handsome young man. When I met the man I found that he claimed to be working at a job in a field that I knew very well. I doubted his veracity.
Since I knew his boss as a friend, I phoned to see if this young man was indeed working at the job in that field. The answer was ‘No’. He had been telling my female friend that he was saving his money for their wedding while they lived on her money.
In good faith, I told my female friend about the reality, that her fiancé did not have the job he claimed to have. She never spoke to me again. And she never spoke to one of our close mutual friends again.
I keep my mouth shut these days and have for the previous 50 years, when someone else's life is about to be screwed up by something I know about.
I doubt that Ann Landers or Dear Abby would give the same advice. I learned a harsh lesson which I will not forget.