The OP privately addressed the issue with the sister, noting that the restaurant choice excluded their wife, who has been vegetarian for twenty years, from enjoying the main offerings. The sister dismissed this concern, suggesting the wife should just eat a salad to ‘take one for the team’ and save the OP a small amount. The OP ultimately cancelled the expensive reservation and instead arranged for catered food at home that everyone could eat, leading to public conflict.

AITAH for canceling a reservation that my sister made for 12 people at a Brazilian steakhouse with the expectation for my vegetarian wife and I to pay for everyone. I said something to my sister privately about not going to Brazilian steakhouses because my wife (of 20 years) can not eat there.
She suggested that I would be able to save a few dollars on the total bill by my wife “taking one for the team” and eating a salad. I instead catered a meal in my home that everyone could eat.
My sister then called me out at dinner for being “a cheap asshole” (the steakhouse is around $100 per person) ate then left with her family of seven.
Conclusion
The central conflict revolves around the OP’s decision to prioritize their wife’s dietary needs and financial boundaries over the sister’s chosen venue and expectation that the OP would subsidize the entire group’s meal. The OP felt unsupported in advocating for their wife, leading them to take unilateral action to resolve the situation.
The core question is whether the OP was justified in canceling the reservation and arranging an alternative meal when faced with a potentially expensive outing that excluded his wife and demanded he pay for others, or if this response was an overreaction to the sister’s poor suggestion. Should the OP have insisted on a compromise location or was catering the only reasonable choice given the circumstances?
Here’s how people reacted:
Although they’re probably should’ve been some sort of discussion between the making of the reservation and the canceling, the fact that she called you out at dinner and accuse you of being cheap in front of your entire family, pretty squarely tips the asshole scale to her side of the meter .
I would say if your sister believes you to be a “cheap asshole”, that relieves you of any need to entertain her family of 7 in the future.
Who gives a fuck if your wife can’t eat there, that’s her decision. Be a champ, take everyone and pay their bill. You should also pay the bills of all the other diners too.
Bring a steak home and wipe it all over your wife’s food and all over her face when she’s sleeping.
FFS.
I think I need to unsub from this sub. The amount of moronic posts.
It would seem from her comments and actions OP your sister thinks your new name is ATM.
Something to consider going forward in your relationship as it’s possible if you look back at your interactions unemotionally with her this isn’t the first time.
Asking for a vegetarian to subsidize meat eaters is rich! She just wants to hurt you.
Imagine how much you’ll be able to save in the future by not having to cater to her entitled family of 7.
Then leave her out of your life.
NTA.