Groom gives bride an ultimatum: 'we invite my sister to the wedding, or the marriage is canceled.' AITA?

"AITA for telling my fiancée I will cancel the marriage and break up with her if we do not invite my sister to our wedding?"

My fiancée and I got engaged a couple of months ago, and we plan on getting married at the end of next year. We have been dating for 5 years, and I couldn’t be happier with her. Now for some backstory, my sister and my fiancée were friends in middle school.

Freshman year of high school, my fiancée’s boyfriend cheated on her with my sister (and by cheating, it was just talking and kissing). Obviously what my sister did was wrong, and this ended their friendship.

But my sister has emotionally matured a lot from high school, and I think this whole thing is overblown. Everyone does stupid stuff in their teenage years, my sister was literally 14 when all this took place.

However, my fiancée still isn’t on speaking terms with my sister, which I’m ok with. My sister has tried to make it up to her many times, but my fiancée is stubborn. However, I do want my sister to attend the wedding and be my best woman. She is the only person in the world I can think of to be by my side at the wedding, as she helped me a lot growing up, and I am where I am today because of her.

But my fiancée doesn’t want my sister to attend the wedding as she thinks it will ruin her special day. That’s where I think she’s going overboard. We’ve had lots of discussions on it, and I finally snapped last night and told my fiancee we’re done if we don’t invite my sister to our wedding.

My fiancée was shocked with what I said and she even cried because I’ve never once bought up the possibility of a break up. AITA for this hard stance?

Here's what top commenters had to say about this one:

gbug37 said:

Besides the wedding, are you really okay with marrying and spending the rest of your life with someone that refuses to speak to your sister, who you have a close relationship with? This is important to consider because it will be a pain point for the rest of your life.

Western-Cupcake-6651 said:

So, your sister betrayed a friend. And that friend is going to be your wife. And you don’t understand why your fiancée isnt breaking her neck to embrace an ex-friend that betrayed her. Because…she betrayed her. She lied, probably snuck around, and showed herself to be a bad person.

Yes, it was a long time ago. But the hurt didn’t evaporate. And rug sweeping her feelings was wrong. And threatening she either eat those feelings or you’ll hurt her by leaving her does nothing but reinforce that your sisters feelings matter more than hers. YTA.

DaddyLonggLegss said:

ESH. Your sister for obvious reasons. Your fiancée for getting in a relationship with the sibling of someone she hates and expecting you to take her side. And you’re absolutely TA for letting this go on for 5 years.

You have been okay with them not being on speaking terms for all this time, but all of a sudden you’re demanding that this change. Where were you thinking of drawing the line, before? What did you expect would happen after you got married and had kids? You accepted a situation for a long time and by allowing this to be the way, you also contributed to the problem.

Schlobidobido said:

ESH. Yes it was a long time ago but still your sister cheated. Just kissing....blah blah...so kissing is not cheating in your opinion? Or not bad? Are you just going to kiss other women when married? Can your maybe future wife just kiss people and it's okay?

Your sister betrayed her friend and that's that. You know your wife doesn't even speak to your sister. You said you're okay with it...then why suddenly insist on her being at the wedding and even your best woman? Save your fianceé some grief and please don't marry. Everyone's better off here that way.

Walterscottjur said:

YTA. There are so many stories on this sub about cheating and how it hurts/changes a person's life and somehow you never thought that your sister cheating with your fiance's ex bf years wouldn't create issues is baffling.

Yes, I get she was 14, but there are just some things that have a lingering effect, and you dont really know how it impacted your fiance. Maybe instead of giving an ultimatum, you should have looked into some couples' counseling on working through it. If this is how you deal with problems, this marriage won't last.

Jazzybranch said:

YTA. I agree that your fiancée needs to maybe get therapy over her feelings of betrayal. I hate all the Redditors saying the fiancé saying should get over it. These same people would hold a grudge if someone bullied them during their teenage years.

Why is that an allowed but fiancée can’t be hurt by her friends actions. The fiancée most likely doesn’t care about the teenage boyfriend but she is unsure of having a person who betrayed her standing up there. It has nothing to do with the teenage boy.

OP talk to her and get her to see reason. Tell her you don’t ever expect her to be friends with your sister but you want your sister to be a part of your special day. See if there is a way she can come to terms with it.