I like to think that she would make an effort to find some common ground eventually.
I like to think that too, but the evidence is somewhat against us. ^_^
I think there is a case to be made for the idea that if he's married to Dinah, she is obligated to treat him as (extended) family.
Weeeeeell. My maternal uncle is a dickweed. And by that, I mean a nasty, bastardly, intolerable excuse for a human being. The way he treats my aunt is simply not acceptable. The way he treats my cousin, only acceptable by comparison. Pretty much everyone in the family hates him. He does come to Christmases and the like, yes - we tolerate him for her sake, he's actually even a pretty fun guy until you see him talk to his wife...
... but it took the family about a decade and a half to get to that point. They thought she deserved better. They didn't like him. They weren't going to pretend otherwise. So, there were a bunch of small fights and then one big fight and then they didn't interact with either of them for the next ten years, to much misery and bitterness for all involved parties.
Obviously, Babs and Dinah are less dysfunctional than my mother's family (and provided you consider GA/BC noncanon, Ollie's probably a better husband than my uncle. Marginally). I'm just saying, "she's family, so her boyfriend is family" doesn't necessarily follow when said boyfriend is not liked by the family. Even if it does involve hurting the actual family member in question.