Um, are people who say "they are good to her because she's the heroine now" really understanding the point of the story so far? They were awful to Yuri because she was the heroine. Their toxic behavior was meant to be "romance" trope. So if Melissa were the target now, with all else being equal, it'd just be her the target of their crap instead of Yuri, but it'd still be the same negative characters.