You know how to spot a cheater: The late nights at the office, the newfound interest in looking good -- and don't even think about getting close to their cellphone.
But what do you do when the two-timer you think you've identified is your good friend's spouse?
That's the difficult dilemma clinical psychologist Joti Samra considered for The Globe and Mail Thursday, after a reader wrote in and shared her sneaking suspicions about a friend's husband.
"From what [my friend has] told me about their relationship, it seems like all the signs are pointing to infidelity," the reader wrote. "She’s asked me what my thoughts are. I think she would be better off without him, but how can I tell her the truth about my feelings?"
Samra's advice to the reader? Unless you have proof, keep your suspicions to yourself.
"They are ultimately the only people who can come to a resolution about how their relationship should unfold," she wrote. "As a result, there is little to no value in sharing your opinions."
We were curious to know if our readers agreed with the psychologist's take, so we decided to ask our Facebook and Twitter communities to weigh in. Turns out, a lot of HuffPost Divorce readers have been in this exact situation -- and others who had been cheated on said they wish their friends would have spoken up. Scroll down to see what they had to say, then head to the comments and tell us what you'd do in this situation.
Should you tell a friend you think their spouse is cheating?
1. "Not if you just THINK they are. Now if you KNOW they are, I think you should go to the spouse that is cheating and let them know you are going to give them the chance to 'fess up but if they don't, then you will." -Randi D.
2. "I was cheated on and have a huge issue with people not saying anything if they know. Several of my 'friends' knew (and even allowed their place to be used for my ex and his girlfriend). I feel that at the very least they should have not condoned it. They should have told him to come clean." -Tara H.
3. "Yes, if you want to ruin two lives." -@MainmacoSeth
4. "I would want someone to tell me, so yes, I would. And would be very hurt by someone keeping it from me." -@TheWonderWords
5. "Nope! I did that once. No hearsay or passing of gossip; I had walked in and caught them being intimate on the floor! I told my friend and she attacked me and never spoke to me again. Lesson learned!" -Lorraine S.
6. "Yes, without a doubt! I was the victim of a cheating spouse and everyone knew before me! Unless you have personally experienced this you can never comprehend the pain and the devastation." -Bob P.
7. "Don't tell. If they reconcile you'll be enemy no.1!" -@kalebogile
8. "Yes, but you need solid proof. And you need to be prepared to lose that friend for a little bit." -@EWrigglesworth
9. "NO NO NO. If they ask, don't lie, but don't volunteer." -@southerner09
10. "I would stay out of it or if you truly care about your friend, I would hire a private investigator and send proof without giving away your identity." -Laura L.
11. "No, no good can come of it." - Barbara H.