Sorry I forgot
Male
Married
As someone who has been there, let me say that I was damn glad that a friend sat me down and told me my wife was cheating on me.
It wasn’t something I could have ever really believed without someone from the outside showing me the cold hard truth. It hurt but it had to be done, and I appreciate this person doing it.
I am male.
Unfortunately I have been in this position a couple of times. One time was a co-worker and I walked into the closet at the wrong time. The other was a friend who decided to spill their guts to me. Both times I was approached and asked to keep it to myself. With the co-worker, it was not a problem, I didn’t know his wife and she was never around.
With my friend, it was a little different. I told my friend that I would not say anything, but I didn’t want to hear anything else about it. I knew enough, and would keep what they told me to myself, however, if someone asked me if I had ever observed the two in a bar or out in public, I would state the truth. My friend accepted that and we are still very close.
Female here. I would tell, simply because I know I’d want to know if it were me!
Keep in mind, the question is about telling the spouse of a friend that your friend is cheating.
Not about telling your friend that their spouse is cheating.
Lots of people would do the second, but very few would do the first.
Personally, I probably would not tell.
If my friend was doing something really dangerous, and I thought that he or she would pass on diseases to their spouse, only then would I tell. And I would try very hard to convince the friend to tell. After all, it is their responsibility.