I really need advice I don’t have anyone I can trust...

My family member is dating someone I just can not click with no matter how hard I try. Things always end in some kind of argument or drama because she’s very passive aggressive and I’m not. I’m not the only one who is not a big fan of hers (she says and does rude things) but because no one else will say anything then I just look like a jerk. My family member wants to marry her and everything so I guess she’s sticking around.

To get to the point, I’m wondering what I should do. I honestly try earnestly to like her and be nice to her but I feel like it always backfires because we don’t mesh well together.

How do I keep her at a distance without someone making it seem like I hate her? Or get accused that I have some motive?

I literally can’t sleep thinking about it and I really would love someone’s advice.

Edit: to clarify, overall she’s not a bad person just a lot of unsavory things. Nor do I go around confronting her all the time.