It's pretty silly, yeah. She's literally just "childhood friend, but better". Also, why is it always a beast girl? Like, in almost every single betrayal manga, the childhood friend who leaves is a blond beauty and the replacement heroine a beast girl. It's not bad or anything, but jesus christ, try to come up with something different for once. That aside she's fine with me.
Still not as good as Gayle though. Gayle best girl.