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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

To tell my sister I don’t like her new boyfriend

173 replies

summerdreams19 · 25/07/2025 12:53

My sister has been dating her new boyfriend for around 10 months now. Initially, I thought he was fine, but I really can’t stand him anymore, and it’s affecting our relationship.

There have been a few incidents, but I’ll share a couple of examples of his behaviour.

For my sister's birthday in June, he wanted to organise a surprise dinner for her with some friends and family. He invited me, providing the time and date, which I accepted. A few days before the dinner, I ran into one of my sister's friends who was also invited, and she mentioned that the dinner had been moved to the next day. She didn’t know I was invited when she told me, and I didn’t mention it to her. My sister's boyfriend never told me about the change in plans, so I assumed I was uninvited. My sister didn’t bring it up, so I don’t think she was aware I was invited either and I chose not to tell her because I didn’t want to ruin her birthday. It’s possible he forgot, but how did he not notice I wasn’t there during or after the meal and why not mention it afterwards?!

Recently, my parents had a BBQ, and this was the second time he met our family. After a few drinks, he became very quiet and distant and wouldn’t speak with anyone (another family member tried to talk to him, but he only responded with one word answers). Eventually, he walked out without saying goodbye to anyone or thanking my parents for the invite. I understand that sometimes people make mistakes when they’ve had a drink, but it’s still early days and he should have been on his best behaviour imo.

My sister has also spent time with his family, and I can’t imagine what they would think if she acted that way.

Usually, I would keep my opinions to myself, but my sister, my nieces, and I spend a lot of time together, and I’ve been avoiding them because he’s always around (either at the house or joining us), and I just can’t bite my tongue or be fake with him. She keeps asking to meet up but I just make excuses.

AIBU

OP posts:
MyLittleNest · 25/07/2025 12:57

Since it is your sister, I would speak up, but I'd suggest you wait until a good opportunity presents itself to broach the topic. If it was just a friend, I probably wouldn't say anything.

Hankunamatata · 25/07/2025 13:00

Neither of those examples are a reason to dislike him. And no you should keep quiet

Why would you assume you were uninvited feom the meal perhaps he assumed your parents would tell you or you could have just asked him, like a normal person?

As to bbq perhaps he got more drunk than intended (not unknown for people to get bit carried away with drink if they are nervous) then he quickly left.

Flowers73752 · 25/07/2025 13:01

I think it's odd that you didn't just message him about the birthday dinner to ask if the date had changed, and instead assumed you had been uninvited...

NachoChip · 25/07/2025 13:02

Both of those instances you have made quite big assumptions about. You chose to miss your sister's birthday to prove a point rather than give him the benefit of the doubt he'd just forgotten to pass on the change?

And the second instance, maybe he was depressed or had just received some bad news. You don't seem to have given him a chance based on your examples and I wonder if there is more to it on your part?

If you genuinely think he's not going to be a good partner to her, then as her sister you should share your concerns, but if you just don't like him for little justification then you need to support your sister and make the effort in her choice of partner.

Pessismistic · 25/07/2025 13:03

If you are close did she ask why you weren’t at her birthday meal? Because I would have asked mine. You could say hey sis I know he’s your bf but does he have to come to everything with us? Just be honest just say I don’t think your bf likes me and it feels awkward for me when he’s there if she asks for example tell her you were originally invited to meal then he rearranged it without telling you so he obviously didn’t want you there. Is he controlling? He sounds like a nightmare but he’s been in her life less than a year whereas you have been in it forever.

Createausername1970 · 25/07/2025 13:03

If you were going to say anything, it should have been right after the BBQ and asked what the issue was.

I would bide my time until the next weird happening and then question it.

The meal may genuinely been an oversight, although I would have been miffed at the time. And for all you know he may have had a bereavement in the last year or so and something at the BBQ triggered a memory. Or he could be a weird, rude twat.

But what is said cannot be unsaid, so don't cause unnecessary friction if he could be around for a few years.

nonevernotever · 25/07/2025 13:04

In the circumstances you mention, particularly since you say he's always around your nieces too, I would bit my tongue and keep a watchful eye. I wouldn't risk alienating her and being cut off from her as a result.

tinytemper66 · 25/07/2025 13:04

What did your sister say when you failed to turn up to her birthday celebration?

Lambswools · 25/07/2025 13:06

I don't think his behaviour sounds terrible, more a bit socially awkward, but you'll know better, having been there.

I don't think there's anything to be gained by saying you don't like him and TBH it doesn't really sound like you've given him a chance.

I absolutely would talk to DSis about the two incidents you describe,just to find outnwhat was behind them. It could be that they'd had a row at your parents and he was walking out rather than do it in public, or maybe that he was annoyed because (he thought) you hadn't turned up for her birthday. Or something else entirely, but if you don't talk to her, you're making assumptions with very little information.

MargaretThursday · 25/07/2025 13:08

Both of those sound a you issue, not him.

He forgot to tell you they'd changed dates- or even asked someone else and they forgot, so you didn't turn up. Maybe friend said to him that they'd told you and he thought that was fine
You were the one making a big thing by assuming you hadn't been invited.

And surely you'd assume that something has upset him if he suddenly went quiet. Not think how rude.

heroinechic · 25/07/2025 13:10

There’s nothing here that seems so bad that you can’t get over it with time. Don’t mention anything to your sister, it’s her boyfriend, not yours. You don’t have to live with him; you just have to tolerate him from time to time.

I would say differently if you thought he was a danger to her in some way.

Meadowfinch · 25/07/2025 13:10

Neither of those things is a crime. He forgot to tell you the date had moved but you knew so I don't understand why you didn't ring him and ask. The only person who was disadvantaged was your dsis.

And some people aren't great after a few drinks. Maybe he's shy in social situations.

Hardly a reason to dislike him. Does your dsis have a track record for choosing wrong'uns? Can't you trust her choice?

summerdreams19 · 25/07/2025 13:12

@Hankunamatata

My parents were on holiday, so they missed the meal. They wouldn't have been aware of it.

The only family members invited were my cousin and me. The rest were friends. My cousin likely didn't realise that I was unaware of the date change, and I personally don’t think it's anyone’s responsibility to communicate messages, except for the host anyway. Of course, I could have asked him, but what if I hadn't run into my sister's friend? It was purely coincidental that I did, otherwise, I would have been none the wiser and turned up at the restaurant on the original date.

Don't you think it would be a little rude if one of your guests just left your party without saying goodbye or thanking you for the invite? My parents put in a lot of work with the food, drinks, and everything, so I feel like that's the least he could have done, whether he was nervous or not.

OP posts:
ConfusedSloth · 25/07/2025 13:13

I feel as though you were determined not to like him.

Imagine he were the OP writing about these scenarios from his side:

  1. "I organised a birthday dinner for my girlfriend, inviting her friends and family. It ended up needing to change dates so I told a few people I'd seen but not everyone. I was checking who knew and who I needed to tell and one friend said they'd already told my girlfriend's sister and she knows the new date so I didn't reach out to tell her. Then she didn't turn up and seems to think I uninvited her because I didn't reach out to tell her the new date - even though I know she was told about the change of date by another guest. She definitely knew about the change because she didn't turn up to the original date either."
  2. "I was at my girlfriend's for a BBQ with her family. I went to the bathroom and checked my phone and saw on Facebook that a close friend from school passed away. I was quite upset but tried to power through at the event. I wasn't very chatty and was quite quiet, I eventually went home. Now my girlfriend's sister doesn't like me" or "I was at my girlfriend's for a BBQ with her family. I developed a pretty bad headache over the evening. I wasn't very chatty and was quite quiet, I eventually went home. Now my girlfriend's sister doesn't like me" or "I was at my girlfriend's for a BBQ with her family. Her uncle was really rude to me and insulted me in a way where I knew I was being spoken about negatively. I didn't make a scene but I wasn't very chatty and was quite quiet after that, I eventually went home. Now my girlfriend's sister doesn't like me"...

You seem determined to take these incidents as personal insults when they almost certainly aren't. It also doesn't make sense that you're very close to your sister and nieces and see them all the time but he only very recently met your family for the second time.

newhouseplans · 25/07/2025 13:15

I can see potential red flags there for sure.

But if he does turn out to be an abusive arsehole, please don't let him manipulate you away from your sister so easily!

Controlling and abusive men want to isolate their victims. If you're going along with this, then your giving him exactly what he wants and leaving your sister increasingly isolated - IF he's doing this - too early to tell for sure, so definitely keep a watchful eye.

Hankunamatata · 25/07/2025 13:16

summerdreams19 · 25/07/2025 13:12

@Hankunamatata

My parents were on holiday, so they missed the meal. They wouldn't have been aware of it.

The only family members invited were my cousin and me. The rest were friends. My cousin likely didn't realise that I was unaware of the date change, and I personally don’t think it's anyone’s responsibility to communicate messages, except for the host anyway. Of course, I could have asked him, but what if I hadn't run into my sister's friend? It was purely coincidental that I did, otherwise, I would have been none the wiser and turned up at the restaurant on the original date.

Don't you think it would be a little rude if one of your guests just left your party without saying goodbye or thanking you for the invite? My parents put in a lot of work with the food, drinks, and everything, so I feel like that's the least he could have done, whether he was nervous or not.

So you deliberately didn't go even knowing the date had changed. Thats really petty

summerdreams19 · 25/07/2025 13:19

@ConfusedSloth

None of those things actually happened though. Also, I’m confused about how you concluded that the friend told him I was aware of the date change? She certainly didn’t. The friend didn’t even know that I was invited in the first place (I said this in my original post).

OP posts:
summerdreams19 · 25/07/2025 13:23

@Hankunamatata

He must have realised after they went out for the meal and I wasn’t there though, so if it was truly an accident on his side, then why didn’t he reach out to me afterwards? I’ve seen him a few times since then. If I were in his shoes, I would have approached the person and said, "I’m sorry, I forgot to mention the date change etc”

OP posts:
ConfusedSloth · 25/07/2025 13:24

summerdreams19 · 25/07/2025 13:19

@ConfusedSloth

None of those things actually happened though. Also, I’m confused about how you concluded that the friend told him I was aware of the date change? She certainly didn’t. The friend didn’t even know that I was invited in the first place (I said this in my original post).

  1. You have no idea if those things happened. All you know is that he was suddenly not chatty and then left. You have absolutely no idea why and have decided, for no reason, that it's because he's an awful rude person rather than the far more likely case that there was a reason why. Just because he didn't disclose the reason to you (why would he?!) doesn't mean there wasn't a valid reason.
  2. You have no idea if the friend told him that you knew. Again, you have no idea. You're choosing to be so certain when you have no idea. She spoke to him to get invited, she spoke to him to get the date change, she spoke to him to attend - she probably spoke to him at other points. You have no idea what else they spoke about. The fact is, you did know about the date change and there's a plausible way for him to know that you knew - so you don't get to be the victim of anything for him not telling you directly. You still knew!

Like I said, you seem absolutely determined not to like him. You sound like very hard work.

Pessismistic · 25/07/2025 13:25

Hey op you don’t need to explain yourself on here the bf has probably done this intentionally how could he have forgotten to message you your her sister. I wonder if he’s controlling if he cares for your sister he would have made sure you were there. Talk to her and if he’s there just casually say did you forget to tell me about the meal changes as I really wanted to be there for my sister’s birthday. See how he responds to that?

Hankunamatata · 25/07/2025 13:25

summerdreams19 · 25/07/2025 13:23

@Hankunamatata

He must have realised after they went out for the meal and I wasn’t there though, so if it was truly an accident on his side, then why didn’t he reach out to me afterwards? I’ve seen him a few times since then. If I were in his shoes, I would have approached the person and said, "I’m sorry, I forgot to mention the date change etc”

Ffs op perhaps he is embarrassed, perhaps he doesn't know what to say. Have you actually spoken to him about it if your that bothered?

Lambswools · 25/07/2025 13:25

summerdreams19 · 25/07/2025 13:12

@Hankunamatata

My parents were on holiday, so they missed the meal. They wouldn't have been aware of it.

The only family members invited were my cousin and me. The rest were friends. My cousin likely didn't realise that I was unaware of the date change, and I personally don’t think it's anyone’s responsibility to communicate messages, except for the host anyway. Of course, I could have asked him, but what if I hadn't run into my sister's friend? It was purely coincidental that I did, otherwise, I would have been none the wiser and turned up at the restaurant on the original date.

Don't you think it would be a little rude if one of your guests just left your party without saying goodbye or thanking you for the invite? My parents put in a lot of work with the food, drinks, and everything, so I feel like that's the least he could have done, whether he was nervous or not.

Yes, it's a "little" rude. It's not the basis for an ongoing grudge or avoiding meeting up with your sister.

ConfusedSloth · 25/07/2025 13:26

summerdreams19 · 25/07/2025 13:23

@Hankunamatata

He must have realised after they went out for the meal and I wasn’t there though, so if it was truly an accident on his side, then why didn’t he reach out to me afterwards? I’ve seen him a few times since then. If I were in his shoes, I would have approached the person and said, "I’m sorry, I forgot to mention the date change etc”

Him: Oh, where's Summerdreams? Oh shit! Did I forget to tell her the change of date?
Cousin: Nah, she knew. I spoke to her about it and she definitely knew it was today.
Him: Oh strange. I wonder why she isn't here...
Cousin/Sister: Don't worry, she's just playing games. She definitely knew about the change of date. Just ignore her - she's always difficult.

Probably what happened.

Dozer · 25/07/2025 13:26

How many times have you met him? Do you have other reasons to dislike him?

I agree he comes across badly from both examples.

It’s poor that your sister has him spending time with her DC after so little time dating.

beAsensible1 · 25/07/2025 13:27

These are pretty low level offences.

Keep quiet.

the best way to approach is to just ask what happened to the bday dinner? And if he was alright as he seems quiet.

just be normal about rather than jumping in that you don’t like him. Most people will be immediately defensive.

it’s all so passive aggressive. Because if I missed my sisters birthday due to misinformation I’d be calling around to find out what happened. Missing your sisters birthday to make a point about her boyfriend is shitty

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