No, I don't think it refers to Athanasia as he said "never have I seen a happy ending result from USING dark magic" so it foreshadows the bad end of the one who cursed her (and possibly Jennette as she was a result of dark magic).
I think I read from another comment before that the Athanasia on earth didn't manage to finish the book (or maybe that was from another manhwa with similar plot I'm also reading). Anyways if so then Jennette might have suffered consequences after the real Athanasia's death that the MC didn't know.
╮(￣▽￣)╭
So like do you know what will happen after chap 45?
Still waiting on the update which is next week
SPOILER
Athy oh Athy, why can't you just be lucky? Damn that novel that she read from her from first life! DAMN THAT NOVEL!
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Okay, now that i made sure it will not be spoiled (hopefully) this is what i want to say (Rant)....So basically, Athy is fated to die...Judging from the recent chapter of 41..Because, the old man said "Never have I seen such a curse with a happy ending".. OH HELL NO. I don't fucking care if we gotta make a deal with a devil! Ain't no way am I gonna see this kid who finally understands how it feels to have a parent die! This kid never had parents in her first life and now she has one. Ain't no curse taking this baby girl happiness! ヽ(`Д´)ﾉ