Disliking brothers fuckbuddy

So, as a sister have you ever disliked one of your brothers female friends. For no apparent reason? like my brother had this fuck buddy and i can't stand her. There's just something about her that's disgust me and pisses me off. I sort of don't like her because one she called me a bitch and two wanted to become my friend to get in his pants, she finally accomplished that last part. Idk just wanted to vent for a bit.