I'm fairly sure my best friend's wife is cheating on him. What to do?

And that is the real root of the MYOB rule.

You don’t know anything about anyone else’s relationship. You may think you do. You’re wrong. A marriage is largely opaque to those outside of it.

Oh, come on. I’m pretty sure I’d know if my best friend were a swinger.

I mean really. We’re talk about a one in a million chance that the OP’s friend is a swinger AND keeps it secret from him.

Suuuuuuure you would.

Yes, but when it is confimed, and you friends say “Yeah, I knew six months ago”, therealization that nobody in your life is loyal to you really sucks.

Thanks to everyone for the input, there’s a lot of wisdom on these boards.

I really like the idea of informing my friend of the facts and then leaving it alone.

I’ll let him know that their friend is parking halfway down the street and is staying overnight while he is out of town. My friend can decide what it means and what he wants to do about it.

Anyone seen the friend go into or come out of that particular house? All I read was that he parks half a block up.

To be fair, unless you’ve seen him go in, and leave in the morning, you don’t really know he’s staying overnight, it just appears that way. Stick to facts that your sister is willing to confirm that she saw with her own eyes, and leave the assumptions to him.

Getting the license plate number is a good idea, unless she saw him personally and can identify him as the friend.

You and your sister need to butt out of this other couple’s marriage and stay out of it.

That sounds like the best bet to me. Besides, you don’t have any solid evidence in any case.

In your shoes I would set it up like a question/joke, to let him know, while at the same time playing stupid.

“MaleBuddy keeps parking his car in front of my sister’s house overnight. Did your wife set him up with a girl in the neighborhood? Like last week (the weekend your buddy was away), he must’ve been there all weekend! Heh, heh, if we don’t get to meet his new squeeze soon, people are gonna start to talk.”

So you can alert him to whatyou’ve seen without making any accusation. If it’s all innocent and he knows the real deal, he’ll probably tell you. If your best friend knows about the afair and approves, he’ll pass on the message to MaleBuddy to find somewhere else to park, so he doesn’t look like a cuckold. If it’s all news to him, he’ll ask you what the hell you’re talking about, and then you can tell him only what you can confirm, that your sister keeps seeing his car parked in front of her house overnight… while he’s away.

But I’d present it as a question as if your buddy is the one who knows the answers. If you state a fact and tell him, you’re the bearer of the bad news. If you ask him then he “figures it out for hiimself.”

That’s the gist of it. The idea being that, if you’ve been burdened with information about a friend being cheated upon, you can either:

  • Give the friend the information you have, risking any irrational shoot-the-messenger backlash, or

  • Keep the secret, becoming complicit in the cheating, while maintaining your hunky-dorey friendship!
    Really, I agree that neither of the options are easy, and that one would probably wish that one didn’t know about the cheating. However, I know which choice I would make, and I know which one I’d want my friends to make, if it were about me.

And this is errant bullshit.

You know how I found out?

I started having pelvic pain and running a fever. My immune system is fairly frail, and I realized I could be having a bout of pelvic inflammatory disease - which can be caused by normal body flora - and asked my boyfriend to take me to the local ER.

Yes, I had PID, and it was caused by trichomoniasis, a sexually transmitted disease. I could only have gotten it from my boyfriend, and he didn’t have it when we both got STD tests at the beginning of our relationship.

Once I wrapped my brain around the concept - because I did not suspect my boyfriend was cheating on me - I broke up with my boyfriend immediately.

A week after that, one of our mutual friends told me that he’d known about the cheating with the woman, and suspected my ex had been cheating with the woman’s boyfriend as well. I hadn’t known because my ex had stopped going to his job so he had time to screw around.

That “friend” and the other members of my social circle knew what was going on, because the woman and her boyfriend had talked openly about it. That “friend” and the other members of my social circle knew I didn’t know about it. I don’t know why none of them chose to tell me. I don’t care. They are no longer my friends, and I suspect that they never were.

So, Mosier, not only is it completely possible for a person to be unaware and unsuspecting of cheating, it doesn’t matter. What they do with the information of their partner’s behavior is their business, but refusing to give them that information is unethical and immoral. Saying otherwise is a cheap cop-out that leaves them vulnerable to physical and emotional harm because you don’t have the balls to put yourself in an uncomfortable situation. Blaming the victim on top of that is incredibly callous.

I would tell the “mutual friend” that he’s been parking in front of your sister’s house. Then he’ll have the choice to come clean to you, or do a better job of hiding his cheating.

Other than that, this isn’t your business. The chances of something bad happening as a result of your getting involved outweigh the chances of something bad happening.

No marriage is improved by a third party acting as a shit-stirrer. In this case, since your sister is involving herself, two shit-stirrers.
Honestly, what do you realistically hope to accomplish by inserting yourself into this situation? All you know is that a car is parking down the block from where your friends live. Actually, you don’t even know that…you just heard it from your sister, who apparently has too much time on her hands if she’s able to monitor who parks where and who is away on business.
Let’s play a little what-if game. Describe how you imagine this all playing out if you go carrying the story to the husband. Please include how you picture the wife, who you also claim as a friend, is going to react.

That’s also why, if I was in the OP’s position, I would ask a question and not suggest an accusation.

Maybe it really is innocent and that the guy met someone in the neighborhood through the OP’s buddy or his wife. And if it’s all truly innocent and the OP says “Hey, I think MaleBuddy has been staying over with your wife.” His pal is going to want to smack him. “How dare you’d even think that my angelic wife was cheating on me! What’s wrong with you? MaleBuddy has been dating NeighborChick since they met at a BBQ at our place. But you’d just assume my wife was cheating on me??? You asshole!”

Asking an "innocent " question that supplies the important facts without implying an accusation will give your buddy the heads up if she’s cheating, or will clarify the real situation (e.g. the guy is dating a neighbor).

I wouldn’t use the last sentence (it’s a bit too “knowing”), but I like the approach of assuming the wife has set him up with someone local.

Yeah, it’s best to hold off on any sly suggestion. Just ask a question while totally assuming complete innocence on everyone’s part.

Yreah, that’ll be just great slipping the topic into conversation like that. I’m sure that the OP and his married friends chat about parking arrangements all the time. Moreover, I’m sure that the OP is_no doubt_an accomplished actor and will be able to deliver the line in a believably offhand and innocent way.
This will end at least one friendship: that between the Op and the supposedly cheating wife. If she and her husband stay together despite the shit-stirring, I expect his friendship with the OP won’t last due to his wife’s dislike.

That’s a very logical way of looking at it. But we are talking about, ahem, affairs of the heart. Logic doesn’t live here anymore. The only thing in play is raw emotion.

Swallowed My Cellphone has the best advice on this.

Your boyfriend stopped going to his job so he could have sex with two other people, who talked openly about it, and you had NO IDEA? Seriously?

I’m not blaming you for being cheated on. I’m not trying to diminish the terrible thing this guy did to you, but the fact you can make coherent sentences and seem to have a solid grasp on the concept of cause and effect proves that you are NOT an idiot.

Seriously.

The two people talking about it did not, of course, talk about it in front of me. They talked about it in front of our mutual “friends” - who neglected to tell me anything.

I was, at the time, commuting an hour to work each way and working all the overtime I could get to pay bills. My ex’s contract at work had ended, and the company had directed everyone to go to training sessions. Proof of attendance was signing a check-off form, which he got a friend to do. So it’s not like there was a sudden reduction in money to explain.

I was fighting a bout of depression, exhausted, socially withdrawn, stressed out, desperate to make my boyfriend happy, and beginning to understand that our relationship was unhealthy. But the one thing I never expected or suspected was that he was cheating on me.

It is possible, Mosier, to be intelligent, coherent, reasonably mature, and not see betrayal coming. I trusted him. He cheated on me. There were no warning signs I was oblivious to, and believe me, I did plenty of soul searching afterwards. I was not in denial. I couldn’t even tell you why he cheated on me, other than he ended up not being a very good human being.

Even if I had been oblivious, if I’d set up camp on the banks of da Nile and thrown myself a party, the people who considered themselves my friends should have made some effort to inform me. If I’d continued partying in oblivion and denial, they’d have been off the hook.

They didn’t.

Their betrayal hurt at least as much as my former boyfriend’s. If I happened to be walking down the street with a bucket of cold piss and saw them on the other side, engulfed in flame, I doubt I’d bother to cross the street and douse them.

So far, several other people who’ve been cheated on have agreed with me - if you know of someone cheating, tell their partner. So far, no one who’s been cheated on has said “don’t bother telling me.”