Questions: Relationships

Between these two options which are you more comfortable communicating through speech?

My girlfriend is really close with her sister, but I'd wager they haven't gotten as close as we have, if you catch my drift.

So while one is clearly more intimate, which one takes precedence? We also spend every waking moment together and have for the past 3 years, while she sees her family only occassionally. Yeah, there's a blood tie, but she admits that her family is really rude and demeaning and she doesn't like spending too much time with them.

For my situation, her sister is extremely rude and just plain mean, so I don't want to spend time with her. Girlfriend is upset that I don't want to see her sister.

But, they are still family. And while we could break up, family is more reliable, sometimes.

I have decided to minimize my time around her family as much as possible, as they are a net-negative to my life. But, I fully support her spending whatever time she wants with them. I'm just wondering how much leeway I should have to bitch about it in the event it damages our relationship. Freedom of choice, sure, but none of us get to decide freedom of outcome resulting from our actions. Does family obviously come first? Or does your romantic partner of 3 years?