Advice on family relationships and sibling dynamics

My brother's girlfriend comes over to our family's house almost every day. Although she rents a room nearby, she stays with us about 3-4 days a week. She doesn’t contribute to anything, from meals to household bills—my family covers all the expenses. She interacts with everyone except me, and I find her behavior rude; I've had a negative impression of her since the beginning. My family is even willing to let her live here and is planning to pay for her upcoming trip with us overseas. As a sibling, am I wrong for disagreeing with this situation? I think it’s important to establish some boundaries. They’ve only been together for less than two years and have had numerous arguments, but that’s their issue. I just wanted to provide some context.