During the match, everyone is wondering how he got better at hand-to-hand combat instead of using his sword as he has been trying his whole life (because he and everyone expected him to be good using the magic sword like his father)
Anyway, he is dominating the fight, but a t some point he uses a special magic only the Demon King had developed. He didn't teach it to him, just show it to him, but MC managed to replicate it to a degree.
The problem is, this unique technique was used by the Demon King to destroy an entire town. Sadith's hometown. She has some post-traumatic issues from seeing the Demon King killing her parents, friends and whole family with it (she survived by a miracle) so she has a panic attack when she sees MC using it.
She downright yells that it was the Demon King's technique, which as followed by the entire audience further hating Earth.
Its only after she wakes up and finds out Earth runs away from home that she starts reconsidering everything about him. Let me be clear: Its not like their relationship is done for. However, as of right now, Sadith desperately wants to talk to him, and Earth runs away from them because he fears to be taken back there, with no chance to further grow as himself.