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Relationships

Mumsnet has not checked the qualifications of anyone posting here. If you need help urgently or expert advice, please see our domestic violence webguide and/or relationships webguide. Many Mumsnetters experiencing domestic abuse have found this thread helpful: Listen up, everybody

Husband suggested opening marriage and mentioned my sister, am I overreacting?

341 replies

Falalalalalala86 · 16/03/2026 18:38

Posting in relationships for more traffic as haven’t been able to stop thinking about this. It feels quite petty compared to some things on here but it’s been playing on my mind all day.

DH and I have been together 12 years, married 7. Two kids (9 and 6). Generally we get on well.

Last night after the kids went to bed he asked if we could talk. I assumed it was something normal (finances, holiday plans etc).

Instead he asked if I’d ever thought about “opening up the marriage”.

I genuinely thought he was joking at first but he was completely serious. He said lots of couples do it now and it can actually make relationships stronger.

I was really taken aback and said absolutely not. He then backtracked a bit and said he was “just curious” and we don’t have to do anything.

But it’s really unsettled me.

I asked where this had come from and he said it was just something he’d been reading about online.

Here’s the bit that’s bothering me though.

When I pushed a bit more he eventually admitted there’s a specific person he was thinking about.

And it’s someone I know.

It’s actually my younger sister.

Apparently she’d joked with him a few weeks ago about “modern relationships” when we were all having drinks and he says that’s what made him start thinking about it.

I feel completely weird about the whole thing now and honestly a bit sick.

He’s saying it was just a hypothetical conversation and I’m massively overreacting.

But I can’t get past the fact that he clearly has been thinking about my sister in that way.

AIBU to think this is completely inappropriate or am I turning something stupid into a huge issue?

OP posts:
ForNoisyCat · 16/03/2026 20:40

Falalalalalala86 · 16/03/2026 18:38

Posting in relationships for more traffic as haven’t been able to stop thinking about this. It feels quite petty compared to some things on here but it’s been playing on my mind all day.

DH and I have been together 12 years, married 7. Two kids (9 and 6). Generally we get on well.

Last night after the kids went to bed he asked if we could talk. I assumed it was something normal (finances, holiday plans etc).

Instead he asked if I’d ever thought about “opening up the marriage”.

I genuinely thought he was joking at first but he was completely serious. He said lots of couples do it now and it can actually make relationships stronger.

I was really taken aback and said absolutely not. He then backtracked a bit and said he was “just curious” and we don’t have to do anything.

But it’s really unsettled me.

I asked where this had come from and he said it was just something he’d been reading about online.

Here’s the bit that’s bothering me though.

When I pushed a bit more he eventually admitted there’s a specific person he was thinking about.

And it’s someone I know.

It’s actually my younger sister.

Apparently she’d joked with him a few weeks ago about “modern relationships” when we were all having drinks and he says that’s what made him start thinking about it.

I feel completely weird about the whole thing now and honestly a bit sick.

He’s saying it was just a hypothetical conversation and I’m massively overreacting.

But I can’t get past the fact that he clearly has been thinking about my sister in that way.

AIBU to think this is completely inappropriate or am I turning something stupid into a huge issue?

what an effing bastard he is!

Soontobesingles · 16/03/2026 20:40

if my husband sat me down and told me wanted to fuck my sister I think my response would be to hand him a suitcase and wave him out the front door.

Sunshineandgrapefruit · 16/03/2026 20:41

I would assume he wants out but doesn't want to be the one that ends it so is looking for a guaranteed way to make you end it.

WonderfulSmith · 16/03/2026 20:41

Tell him that sounds like a great idea and can he mind the kids while you go out tomorrow night to get fucked senseless by Steve from marketing.

wishfulthinking25 · 16/03/2026 20:42

TheSpottedZebra · 16/03/2026 18:39

A huge issue for me. As in, probably marriage-ending.

Second this

Imbusytodaysorry · 16/03/2026 20:43

@Falalalalalala86 wow ! Could it actually get any worse . This you can’t come back fr surely !?
He has ruined your life together and relationship . All he had to do was show you the real him.
He is a creep . Any decent person does not look at their kids aunty / son idea sister in that way. He has massively over stepped. .
Your sister made a joke and now he think he can get to shag a younger women as he feels she is up for it .

You need to get your ducks in a row and if honestly be getting an std check as this hasn’t came from nowhere .

Viviennemary · 16/03/2026 20:43

How can you stay with this awful man. Surely this is the end of the marriage. Let him go and live out his little fantasy even if its only in his head.

Pedallleur · 16/03/2026 20:46

Does he think/know she is interested? At least you know what his internet search history will show and what he is thinking about when having sex.

Mischance · 16/03/2026 20:46

Tell him to jog on ....

Arregaithel · 16/03/2026 20:47

Falalalalalala86 · 16/03/2026 19:55

Just to add, my sister wouldn’t be interested in him anyway which is the main point. I don’t even think she particularly likes him that much, never mind fancy him.

" I don’t even think she particularly likes him that much, never mind fancy him"

That old chestnut!

Yes @Falalalalalala86, I am, absolutely, a sceptic, so give whatever weight to my view as you're happy with

Just be mindful though @Falalalalalala86 you know them both.

brassbellsandcockleshells · 16/03/2026 20:48

Your DH, OP not only wants to open up your marriage but also the biggest can of worms you've ever seen.

A good friend of mine's exH had an affair with her younger (single) sister when she (friend) was pregnant.

The mother took the younger sister's side 😮which resulted in my friend not speaking to any of her immediate family for 30 years.
She only spoke to them when her mother contacted her to say her father was dying and pleaded with her to visit him.
She went to see him for an hour and hasn't spoken to any of them since.

I can't advise you what to do, but you need to know what the fallout from this could be and be prepared.

Owly11 · 16/03/2026 20:49

Urgh. No I couldn't get past this. Your husband wanting to have sex with your sister. No. Apart from being absolutely gross it shows that he has absolutely no conception of you as a separate real person with your own thoughts and feelings. He sees you as an object and not only is he unable to put himself in your shoes, he doesn't even realise that this is an essential ingredient of any relationship. He sounds highly narcissistic.

Newusername0 · 16/03/2026 20:49

Genuinely marriage ending!

brassbellsandcockleshells · 16/03/2026 20:49

wishfulthinking25 · 16/03/2026 20:42

Second this

Me too.

Pedallleur · 16/03/2026 20:51

Falalalalalala86 · 16/03/2026 19:53

Thanks so much for all the replies. I’m still going through them. I’m not contemplating an open marriage in any way. I’ve always been very content with monogamy and if he wants to shag someone else, he can jog on! I’m still not 100% if he was just joking. I think he was serious about wanting the open marriage but maybe just joking about it being with my sister

There are lines you don't cross but he did. He was testing you out.

gamerchick · 16/03/2026 20:51

If be telling the sister that your husband has asked permission to fuck her and let her deal with him.

He can deal with some regrets for a bit.

Frostynoman · 16/03/2026 20:54

Has he made a habit of minimising your very fair concerns and reactions throughout your marriage or just for wanting to shag your sister?

greengreengrass3 · 16/03/2026 20:54

There’s not much that shocks me but WOW, this is a huge issue. I don’t think I could get over this!

loislovesstewie · 16/03/2026 20:54

I think you can take it that he was being serious. I would tell him he's quite free to chase her and you will be ensuring that he is free to do so. And I'd be off to the solicitor tomorrow. That's so yuk I couldn't share a bed with him ever again. Much less have sex with him.

BauhausOfEliott · 16/03/2026 20:55

Falalalalalala86 · 16/03/2026 19:53

Thanks so much for all the replies. I’m still going through them. I’m not contemplating an open marriage in any way. I’ve always been very content with monogamy and if he wants to shag someone else, he can jog on! I’m still not 100% if he was just joking. I think he was serious about wanting the open marriage but maybe just joking about it being with my sister

I’m still not 100% if he was just joking. I think he was serious about wanting the open marriage but maybe just joking about it being with my sister

Surely if he was joking he’d have clarified that after you’d reacted in horror?

Also, it seems insane to me that someone would make that particular joke just after making a genuine suggestion to have an open marriage.

Frankly your husband sounds mad.

pizzaHeart · 16/03/2026 20:56

Agree with others that it’s sickening thought and the one which would mean the end of marriage for me.

By the way it’s probably worth having a conversation with your sister. It could be that she was joking without even second thought but your DH got it absolutely wrong thinking that he was such a “prize” for everyone.

Waitingfordoggo · 16/03/2026 21:00

The audacity! I can’t fathom how or why he thought: ‘I know, I’ll suggest this to my wife. She might just go for it’. What an utterly crass, disrespectful and stupid man. Sorry, I’d be running for the hills.

OneDogTwoCatsHalfaDH · 16/03/2026 21:00

PyongyangKipperbang · 16/03/2026 20:33

I read this article last month and someone kindly c&p'd it

https://www.mumsnet.com/talk/_chat/5489399-brilliant-article-on-open-marriages-in-the-i-anyone-got-a-sub

Its a few posts in but basically it says that men who suggest this are seriously overestimating their value on the open market.

Haha, yes, my ex persuaded me to try an open relationship.
Turned out I got a lot more takers than he did!

And if h had ever suggested my sister OP it would have been a relationship ender.

brassbellsandcockleshells · 16/03/2026 21:01

WonderfulSmith · 16/03/2026 20:41

Tell him that sounds like a great idea and can he mind the kids while you go out tomorrow night to get fucked senseless by Steve from marketing.

😆😆😆

Evasmissingletter · 16/03/2026 21:02

Ewwww . Couldn’t get over this