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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

Aibu to think boyfriend was with his brothers girlfriend?

33 replies

erinS93 · 26/08/2026 10:20

So does anyone else find this odd? I’ve been with my partner a year. And I haven’t met his brother. He told me a story of how they randomly stopped speakin and don’t even have each other on any social media anymore and how they where really really close etc. my boyfriend told me he is nearly sure his brother slept with his ex wife. (My boyfriend and his ex wife have been split for 3 years) he told me how they used to go out all the time and there was one time he seen a picture of his ex’s boobs in his brothers phone. So he said she obviously sent the brother that. But then I’m over thinking that the reason that they don’t speak is something to do with my boyfriend sleeping with his brothers girlfriend? He maybe done it on badness if he thinks he was with his ex wife. Aibu to overthink this? Aibu

OP posts:
Thirteenblackcats · 26/08/2026 10:35

without any evidence im not sure how you could reach that conclusion. You could always ask his brother though

BMW58 · 26/08/2026 10:36

Why do you think he's done that?

SunnyRedSnail · 26/08/2026 10:37

Does it matter?

Mycatmax · 26/08/2026 10:37

Eh?

Wherethedogsits · 26/08/2026 10:41

Your boyfriends brother maybe slept with your boyfriends now ex wife and you think that your boyfriend slept with his brothers girlfriend as retaliation?

Sounds exciting!

NearlyNewNonny · 26/08/2026 10:41

Isn't it more likely the brother slept with his wife? There's nothing there to say your partner slept with his GF.

GladBiscuit · 26/08/2026 10:50

So you think he is deflecting because he was the one who actually did the dirty, à la Bridget Jones? That’s quite a reach but you clearly don’t trust your boyfriend to be honest, do you trust him in other areas?

thisismeithinkorisit · 26/08/2026 11:04

What is it about your brother than makes you think he's a liar and a cheat?

ColdAsAWitches · 26/08/2026 11:05

No, you're being mental. There nothing suggesting the massive leap you've taken.

MoonChime · 26/08/2026 11:07

You must have been treated really poorly previously for you to turn this around to your boyfriend being a cheater.

Or this isn’t the full story.

calbum · 26/08/2026 11:14

YABU because you haven’t given a single shred of detail that could possibly indicate this happened. Unless you have forgotten to add the crucial detail I think probably your boyfriend hasn’t done anything wrong. That said, if you really have just imagined up an entire reverse with zero cause to do so you probably need to end the relationship.

AlliWantIsARoomSomewheeeere · 26/08/2026 13:22

You are going to need to explain how you got to that conclusion I'd you want any useful advice...

Cos the info you have given is either missing a massive chunk of the story (there is NOTHING you have said that implies that) or you have some massive trust issues that need therapy before you are doing to be able to be in a healthy relation.

AbsintheMakesTheHeartGrowFonder · 26/08/2026 14:18

This entire thing sounds completely mental.

erinS93 · 26/08/2026 15:19

AlliWantIsARoomSomewheeeere · 26/08/2026 13:22

You are going to need to explain how you got to that conclusion I'd you want any useful advice...

Cos the info you have given is either missing a massive chunk of the story (there is NOTHING you have said that implies that) or you have some massive trust issues that need therapy before you are doing to be able to be in a healthy relation.

Yeah nothin he has spoke about her before etc and said she’s a nice girl and that’s all he’s mentioned. But he just randomly said him and the brother stopped speaking. But the brother just follows him on insta

OP posts:
TheBroonOneAndTheWhiteOne · 26/08/2026 15:37

erinS93 · 26/08/2026 15:19

Yeah nothin he has spoke about her before etc and said she’s a nice girl and that’s all he’s mentioned. But he just randomly said him and the brother stopped speaking. But the brother just follows him on insta

And?

Cherry8809 · 26/08/2026 16:35

I’m bored, let’s go to therapy 💁🏻‍♀️

ColdAsAWitches · 26/08/2026 16:55

erinS93 · 26/08/2026 15:19

Yeah nothin he has spoke about her before etc and said she’s a nice girl and that’s all he’s mentioned. But he just randomly said him and the brother stopped speaking. But the brother just follows him on insta

So what makes you think he's slept with her? You've got nothing except your own paranoia!

Additup · 26/08/2026 23:10

Tbh even if your bf did sleep with his brothers gf, so what? Presumably it was before you met 🤷‍♀️

erinS93 · 26/08/2026 23:35

Additup · 26/08/2026 23:10

Tbh even if your bf did sleep with his brothers gf, so what? Presumably it was before you met 🤷‍♀️

It would mean he’s a scumbag? If he can sleep with his own flesh and bloods girlfriend. And I wouldn’t wanna be with someone like that

OP posts:
BadLad · 26/08/2026 23:45

Is your boyfriend Ryan Giggs?

Thecatspantaloons · 27/08/2026 00:08

I'm not the gossipy , drama loving type but to ask what does it matter sounds a bit obliviously above it all.
I would be curious, so I could avoid future bs and possibly breeding with ferals.

erinS93 · 27/08/2026 00:10

Thecatspantaloons · 27/08/2026 00:08

I'm not the gossipy , drama loving type but to ask what does it matter sounds a bit obliviously above it all.
I would be curious, so I could avoid future bs and possibly breeding with ferals.

I know I can’t believe girls saying what does it matter. It matters cause I don’t want to go with a scumbag Even if it was a million years before me 🤣

OP posts:
InterestedDad37 · 27/08/2026 00:13

Need a diagram, with arrows and stuff.

CamillaMcCauley · 27/08/2026 00:14

Right… so you’ve just made this possibility up in your head and there’s absolutely no real-life evidence for it?

PollyBell · 27/08/2026 00:21

Do you not want more out of your life than this, we are told women are highly inteliigent capable beings why are not seeing more of this?