"I'm the hated villainess" and it's a character who does nothing wrong and dies tragically, and the solution to that tragic death is "just don't alt-f4". words used to mean something. Now mangaka will call a character a villainess for frowning in the background while the original heroine steals her grandmother's jewelry and farts on her dog.
If this wasn't an isekai and she was jus a normal girl whodheard gossip about him, it would change literally nothing about the story or dynamic. The only thing it would lose is clickbaiing the audience with "villainess".