There's quite a bit of background and story to this, so I'll try and made a condensed TL;DR at the end.

I am the eldest of 5 siblings, 3 girls and 2 boys.  We were raised to value our family and each other, and are quite close due to this. 
 This past weekend, my first brother finally got married to his SO of 12 years.  My second brother was his best man.  He was very honored and excited to fulfill this role for our brother.

My second brother has been dating his gf for about 2 years now.  They met at the small grocery store where they worked together, and she still works there while my brother has moved on.  Mom and my youngest sister, who is very close with this brother didn't like her from the start, claiming she was self centered, gross (due to being a smoker), slutty (because she was known to have sex with her previous bfs), and using him (brother is generous and old school romantic, and frequently helps buy her groceries, helps finance things she wants here and there, and spoils her on her birthday and holidays.  AFAIK she reciprocates in kind to him on holidays and his birthday, so in this case I know it's just my mom and sister being judgementaly bitchy).  Mom and sis also hate that they're sexually active and that he wants to move in with her after graduating college next year.  For the record, I personally don't care, but was a little squicked out when they did it at the house we 3 (me, youngest sis, and second brother) lived at because he has the basement suite (it's fully finished) and it carried up through the vents, so we heard....everything.  Other than that awkward instance, I have had no issues with him dating her, or her personally, I think she's perfectly nice, but don't see her often as they prefer to hang out at her place.

So, as stated before, family is very important to all of us 5 kids.  We frequently have get togethers for birthdays and holidays, and sometimes everyone goes to mom's house for a meal because she wants to see us.  Those with SOs generally bring them along once the relationship starts getting off the ground, which I am lead to believe is generally the norm.  The thing is, this young lady barely attends anything.  Despite what they say about her when she and brother are not around, mom and sis have never shown any hint of this hostility the few times when she has been.  It's a little coincidental too, that when she does come to things it's usually something like Christmas or Easter, when she's guaranteed to get something.  When it's something like a meal or a small gathering for a birthday (some siblings live out of state, so who ever is in town usually goes), her "anxiety" flares up and she can't go.

Now, I won't say that she doesn't have anxiety.  Many people do.  It just seems strange that it prevents her from coming to a meal with people she knows and who go out of their way to make sure everyone is comfortable at the event, and not from her cashier job at a very busy grocery store where the majority of customers will get very pissy if you're not fast enough, or the item won't scan, or what have you.  She'll attend work parties and meet friends at bars frequently too with no issue.  Again, I'm not saying she doesn't have anxiety, or that it can't apply to the family situations specifically.  From an outsider's perspective it simply seems fishy.  That, and there was an instance when she claimed anxiety to not come to a get together only to go to the mall with work friends instead.  It was posted on facebook for everyone to see, even.  By the way, my brother attends all her family gatherings and parties with no issues.

So, knowing this, it was incredibly important for my brother for her to come to the wedding.  This is his only brother- he will never have the chance to be best man for him again (assuming all goes well with the marriage, obviously).  He was absolutely devastated when she told him she wasn't coming.  She absolutely knew how important this was to him.  She knows how important family is to him.  She says she loves him, so if that's true, why the hell didn't she even try?  I am autistic and have dealt with anxiety myself as well.  I was a bridesmaid.  I was given accommodations at the hotel where the reception was held to get away from all the noise and stress.  I know my brother would have assured her that any accommodations could and would be available for her as well.  So long as she was able to go, even if for just a little while, it would have meant the world to him.

So I ask you, reddit- Are We the Assholes for being mad that she didn't come to the wedding?

**TL;DR** Brother's GF of 2 years did not attend our only other brother's wedding, where said brother was best man.  It was a very important event to him and our family and we're hurt and angry with her for not even trying for his sake.  Are we the assholes here?