When I was married in any dispute with ex's family either he didn't have enough info, or they were right, or that was the way they were and I'd have to suck it up. I do not regret that divorce. I do regret holding on for too long.
Me too .
Apparently I'm in the minority here, but here's my two cents anyways. I think that would be a recipe for failure. Having your spouse's back is great as long as he/she is right. If you have a great family and you get along with them fantastically (as I do), I would go so far as to say that standing up to your family for the sake of a girl is dead wrong, even if she is right. That would only send all kinds of wrong signals to her. Maybe she'll express her happiness for a short period of time, but eventually she'll lose all respect for you. What are you gonna do if things don't work out for you two? You're gonna lose her and you have already lost your family. I would rather lose the former than the latter.
I hope if she is being an idiot, you wouldn't dime her out in public, but would tell her she's wrong in private. Loyalty is great, but honesty and integrity is important also.
That is having her back. Having someones back doesn't mean you think they're always right, it means supporting them publically and privately. Pointing out that you disagree, in private, is not going against that. It is still supporting them.