I suspect that my friend's spouse is cheating. Should I tell my friend about my suspicions?
Wouldn't you want to know? In fact, you should tell them before you talk to anyone else about it. Don't participate in gossip; your friend deserves better than that from you. But if you really think something might be happening, you should warn them.
Don't pretend to know more than you do. Unless you know solid facts, admit that you might be wrong and then just tell them what you suspect and why you suspect it.
