'AITA if I ditch my GF's bday party because she enabled her brother cheating with her BFF?' UPDATED

"WIBTA if I cancel my GF's birthday which starts in 12 hours?"

Everyone involved is in the 25-30 years old range. Tomorrow, or rather in 12 hours, we have a family picknick and I just don't feel like going anymore.

Here's the thing. We had an absolute blast of a birthday today. A quality over quantity day which I will cherish forever. Until her brother started kissing GF's best friend. My girlfriend tried to matchmake them several years ago, but it never had any lift-off. Admittedly, they have the potential to be a great couple. What that set me off is that her brother is married. And has a kid.

When the involved friend just went to kiss my girlfriend's brother he went along with it. I can understand that, I truly do. Mistakes happen, especially under the influence of mind elevating substances. However, going back for more is crossing the boundary of it being a moment of weakness.

What amazed me the most was that her friends were cheering them on. The wife of the brother is a bit of a hermit. The friend of my GF is fun, attractive and social, so of course everybody would love to see them together. I was appalled by the 'positive' reactions of (nearly) everybody.

Yet still, I kept my mouth shut and enjoyed the rest of the evening. He is an adult and it is none of my business. He knew what he was doing and the wife is aware of a history of comparable behaviour. If such a relationship works for them, then why should I choose to intervene and smite them with my sword of subjective justice?

What I could not accept is that my GF offered them her bedroom and we would sleep in the living room on a pull-out bed. It's her appartment, so it's her say. That is not the issue. The issue is that the person I trust and love stimulates immoral behaviour, because she would love to see her best friend together with her brother.

The brother, his wife and his kid are attending the family birthday picnic tomorrow. The image of sitting there and seeing them started to loop over and over in my head, so I packed my stuff after we already went to bed.

She tried to figure out what was bothering me while I was packing my stuff. I explained what was gnawing at me, and her reply simply was "oh you just don't understand". Well, maybe I don't. Maybe I really don't.

I do not know what to do. I really don't want to go tomorrow. There is so many things that make me angry, sad, and another range of emotions which currently are exacerbated by drugs/alcohol. But still.. I wonder if I feel the same tomorrow when I'm sobered up. Her birthday is really important to her. I'm starting to severely doubt myself here. I'm not a black and white kinda guy, atleast I hope I'm not.

My truth is: He cheated on his wife. It is not a mere mistake if you go back for more. The facts are: The friend of GF went in for the initial kiss. He went looking for more several times. So, WIBTA if I cancel going to the birthday tomorrow?

What do you think? AITA? This is what top commenters had to say:

[deleted] said:

NTA. Id feel the same about interacting with the brother’s wife. I can’t be duplicitous like that. I think you’ve got some serious thinking to do about your girlfriend. It looks like you two have a major disagreement about affairs.

LadyTherion said:

NTA I would seriously reconsider your relationship if she's that excited about cheating.

dobbysreward said:

NTA. Adults don't get a magic halo over their birthday that protects them from the consequences of their actions. Talk to her and ask her to explain why you don't understand. If they have an open relationship, ask if you can confirm that with the wife. If not, then your relationship with your GF is probably over anyway. How do you trust someone who openly encourages cheating?

MISSdragonladybitch said:

NTA You just learned something really, really serious about your girlfriend's morals and how she treats relationships. You've also learned that her brother is a cheating sack of shit and she's downright perky about that. I'd be wondering if this is the mindset of their whole family.

I not only wouldn't go, I'd seriously rethink the entire relationship, seeing as how they're both so giddy at the idea of trading up, and don't give a shit about the feelings of anyone else, prior commitments or even that there's a child involved. Major, major red flags here and it doesn't matter what day it is, you've just been hit by something huge and need some time.

DickPigAlberta said:

INFO; is it possible him and his wife have an arrangement if this behavior is common and she knows about it?

OP responded:

There is always a possibility, although I have not heard of such an arrangement so far. If there is, I am clearly in the wrong and will sincerely apologise for my reactions.

bossyjudge said:

NTA. That is not ok. You need to tell her you are not ok with what happened and you are not ok with her encouragement of it. I wouldn’t want to attend either.

tadanohakujin said:

INFO: Will you be cancelling the birthday event, or just not be going to it? I wouldn’t go either tbh, that sounds very uncomfortable to me, unless the brother and his wife are in an open relationship...? Drugs and alcohol make people stupid man, but it doesn’t excuse cheating.

OP responded:

Sorry for not being clear. I meant that I won't be attending, because I can't get the image out of my head of pretending nothing happened when I see the wife and kid. I grew up with a father who was loose around women and a mother who pretended nothing happened. They had the happiest unhappy relationship. Therefore, it might hit me a bit harder than someone without that experience.

Concerning the brother's relationship: There is always the possibility there is an open relationship. I highly doubt it. I just remembered the wife prefers him to 'hermit' along with him, while he prefers to go out. Open relationship and a preference to hermitting sounds a bit contradictive, but I admit that I'm making a large assumption.

And ladypoe1207-0824 said:

NTA, and honestly, I don't think I could continue to be in a relationship with someone who condones, even encourages, infidelity. It's disgusting and I've ended friendships over them cheating.

Update:

I would like to thank everyone for sharing their honest opinions, experiences and insights. I have gained a bit more information about the whole ordeal, and I feel satisfied with the answers I have received. To an extent.

Context:Brother is in the country for a couple of months. Wife and kid came along. I was unintentionally left in the dark concerning some information, but there seems to be a 'sweeping it under the rug' kind of mentality, and as I've understood so far the wife participates in that. Fine. But I do not consider that an open relationship.

Being left in the dark and having to see the experience unfold in front of me and being informed about it in hindsight is disconcerning to me. However, it is something I usually am able to cope with, as I deem the awareness part on the wife's side the most important aspect of it all. In addition, with that information I am able to understand what the motivation of my girlfriend is.

She stated she would not accept them having sex in her bed. The friend who initiated was having a 'bad trip' of sorts and they were comforting each other. Again, fine. The chronological facts, personality of the friend and miscommunication all line up.

Now here is what is gnawing at me. He has been in the country for X amount of months. There were 'friends' in the room who were more distanced to the complex aspects of their relationship , but in order to react to the situation must have been:A. Aware of the situation and therefore could morally justify the actions (even I don't fully agree with it, I can still understand and therefore cope);

B. Unaware and therefore had an intersubjective (and immoral from my perspective) opinion that the initiating friend was a good trade-up, because she's more fun, X, Y and Z;

C. Fill in your option in the comments.

Fine. But!

I am a foreigner in this country, isolated from my own friends and family for more than 14.000 kilometers. These are her close friends, but I love them nonetheless as my own. I just have strong beliefs that if the relationship breaks up, our social network will naturally be more inclined to take her side.

I do not resent that thought nor act upon it, but I keep it in the back of my head as a realistic scenario. Please criticise this thought if you think I am wrong, I am here to learn.

People consider me fun to hang out with, social, helpful and kind, but I am introverted (INTP). Social experiences drain me, but I do enjoy them and certainly try to add value to gatherings. I just can't keep up with a large consecutive quantity of social events.

What if the day comes friends think that Mr. SomeGuyInTheFuture is a more suitable partner because they perceive him as more fun, X, Y and Z? Will they condone, encourage or even provoke a break up?

Yes, this sounds anxious. Maybe even paranoid. I hope that in a way it also sounds realistic. Again, please criticise if you do not agree or if I'm looking through a micrososcopic lens where the use of a telescope might be more suitable.

I promise to keep you guys updated concerning the follow up events. Right now I just need time to think about my feelings related to the update of the post. I truly value all of your opinions and it helps me get out of my echo chamber and have a constructive conversation with my partner.

My sincere gratitude.

Second update:

I did not go to the family picnic in the end. I felt horrible and physically sick, and not because of the preceding massive bender.