Just an observation (can be wrong)

Remember when jennette's aunt framed athanasia for jennette's poisoning(athanasia first timeline),it was not because her(jennette)aunt feared that athanasia will take the throne someday, it was because she(for some reason idk) found out that Ijrkiel fell in love with athanasia at first sight so jennette's aunt just cleared the path for her niece by framing athanasia and then she died. In her first timeline It was shown that when jennette introduced Ijrkiel (idk which chapter) to athanasia he fell in love with her at first sight, he was blushing and constantly staring at her forgetting about he surrounding. Even in athanasia's present timeline Ijekiel still fall for her and thought of jennette as just sister but in the first timeline he just followed his father blindly and accepted jennette as her fiancee. I can be wrong but this is the only possible reason for athanasia death in her first timeline.