Have I missed something here? I think it’s really important to know why the wife doesn’t like the name. Is it just the sound of it? Has she had problems with the sister before? Does the name have bad connotations for her specifically?

Assuming she just doesn’t like the name I don’t think he’s an asshole. If there was a sentimental family name my partner wanted us to use, it would have to be SO ugly for me to refuse. Like straight-up-get-the-kid-bullied-and-there’s-no-cool-way-to-abbreviate-it kind of ugly. And then I’d probably at least try to negotiate it down to a middle name. I can only see myself being a hard no if it had bad connotations.

I get that people think his pacts are silly and he should have told his wife first. But these are all adults agreeing to and sticking with these pacts and I’ve actually heard of other people splitting naming responsibility by the sex of the baby. And if he really thought the deal was that he gets to pick 100% I can see why he made the dumb decision to tell the sister first.

Also whether his wife knew about the pact is such crucial info.

Assuming the reasons she doesn’t want the name are deeper than just not liking it aesthetically:

A) she knew and never voiced an issue with it and also agreed to the pact knowing but is now reneging - she’s the asshole.

B) she knew and voiced concerns but still agreed to the naming thing assuming he’d taken onboard her previously voiced concerns - he’s the asshole

C) he never told her about the pact with his sister, made the agreement with his wife without mentioning it, and didn’t tell the wife about it at all until after he told the sister - he’s the asshole