From what I’ve read, it probably wouldn’t be classified as rape if, for example, Flashback was the one who did it. I’m basing that off of this paragraph:
“In South Korea, sexual activity with a person under the age of 16 (in international age, not "Korean age") is considered statutory rape, unless the other party is under 19. Sex with a child under 13 is considered statutory rape under all circumstances. Prior to 2020 the age of consent in South Korea was 13.”
I’m not saying this makes it ok, and the “internal ejaculation” without consent part is definitely not ok, but perhaps the age difference was not a concern for the people involved. The other stuff (cheating, attitude) isn’t really worthy of a scandal on its own.