That happens, but interestingly enough when I read the first post I was kind of thinking maybe it wasn't as bad as you were thinking. Also though is your brother like interested in a potential relationship with her or just friends?

me and my brother are pretty close but when he is into a girl and potentially wants to date them he will get a bit distant just because he's focusing on that and might not hang out with me as much since he wants to see them and would feel akward bringing his sister along for meeting a girl which I totally understand...I probably wouldn't want to bring him if I was going on a potential date. Not sure if that's relevant to your situation though.