Dear Carolyn: I work with a close friend's husband and am friends with both of them, though the wife has been my go-to adviser. Her husband has cheated on her before, and I spent countless hours talking to her about this, encouraging a second chance for him and stressing how much she had to lose if she chose to divorce. (There were young kids involved at the time.) This was undoubtedly colored by my own painful experience with divorce.

From what I've witnessed and heard at work, the husband is cheating again. I want to tell the wife, but it's not my place. I'm p----- as hell at the husband, especially since I championed his cause previously. I feel responsible to the wife for my previous encouragement to stay and work things out.

I am not sure what if anything I can do.

— Friend

Friend: You can learn from hard experience.

You got too involved last time. You obviously meant well and care deeply for this couple — but you also took a firm position on what the wife needed based on your own experience, instead of listening to her and letting her needs and circumstances determine the best course of action for her. You had your thumb on the scale.

You recognize that now — which is good, and important.

So apply it. You have not been forced into the middle here — you don’t have direct knowledge of the husband’s actions and no one has asked your opinion — so stay right where you are: out of it.

If he’s cheating, if the wife finds out, and if she asks what you know, then you tell the truth — that you had your suspicions but none founded enough to speak up, and would not risk her marriage or anyone’s on a hunch.

Things get acutely difficult if you ever do acquire that direct knowledge, because that puts two important realities — that withholding information from friends about their lives makes you a liar of omission, and that other people’s marriages are none of your business — in direct conflict.

When that happens, your only viable option is to try to anticipate what your friend would want. As I said — so difficult. One person’s idea of friendship is to have friends who get involved, and another’s is to have friends who know not to.

But if that happens, this is a riddle old enough to have an established set of line-walking steps: 1. Tell the husband what you know and why you’re furious at him for it; 2. Tell him he has [a window of time] to fix this himself before you act for him; 3. If he fails, then tell the wife she needs to talk to her husband. Your goal is for him to be the messenger.

My favorite step: 4. Hope fiercely that your friends don’t project their beefs with each other onto you, since you’re so very conveniently placed for that. And much easier to resent than each other.

Runner-up: 5. Give your friendship with the husband a hard look. We are all works in progress, but if he’s doing what you think he’s doing, then he’s also opting not to progress.

Write to Carolyn Hax at tellme@washpost.com. Get her column delivered to your inbox each morning at wapo.st/haxpost.