It's unfortunate, but this is one of the major conflicts that drives the story. It doesn't get resolved until somewhere in the 2nd half of the story when the truth is revealed.
Does this mean nayoon and hajin will become enemies
Pretty much cause it gets reveal that Hajin kills her brother, causing him to become a fugitive while living at the Troupe's base and also this house that he got with Evandel. Then, we get a few years' time skip with everyone having joined their respective guilds or organizations.
They do somewhat patch things up when Nayoon confronts the truth of why Hajin had to kill him.
Is he going to kill Nayoon's brother for real?
Man. If that happen, idk how broken Nayoon's feeling is. This is intriguing