Comment by creek on AshiuRey

@creek that might be one of the reason but i think the main reason was she really thought he became a demonic human with his own will and betrayed humanity until she found out that he's manipulated by his sister (heavenly demon) and has a cursed put in his heart when he died by confessing the locations of the remaining demonic human causing his heart to burst. You can check it in the first chapter, he even said in his monologue before dying that if he told them that all that he has done was against his will and manipulated from the very beginning, would they forgive him? By the time Seol-Ah learned the truth she felt guilty and regretted she didn't notice it from the beginning that's why she did everything to turn back time. Novel readers said that Soel-Ah and the heavenly demon worked together to bring him back to the past idk if it's true.

@creek You mean when they were in the Demon Realm? Unless Wi SeolHa remembers it, Yangcheon mentioned that they all regressed to the day before being sent there and no one except him remembered anything. Given what we know of Seol Ha by now, it's possible she does remember and just played it safe. But between being send off and regressing, there could have been something that caused him to become a demon.

And this is why I hope this story won't stall 'cause it has a really good passing.