
I agree. Jieun and Aristia both are actually doing the same thing, they're acting on the previous Ruve's behavior. Both refuse to love him because of how bad he was, but I think there was a point where it was mentioned Jieun didn't actually love him (or at least not) and the poisoning just made sure she never would love him.
I just don't think Jieun would be THIS scorned if she knew Ruve's behavior was because of a mind altering substance that HER side used. The old dude would manipulate and use Jieun easily, but I doubt he ever was open about his methods.
Not that I LIKE the Jieun so far. But I think she was just so desperate to survive in a new world where everyone was pushing her into such a complicated role, she allowed herself to remain ignorant and ended up getting played. I'm sure she'll realize everything eventually and be like Frenemies with Aristia, assuming she never returns to her world.
So the prince was drugged and manipulated just like Tia was, only she was a different kind of political target. Once Tia and her father were out of the way, drugs and alcohol ensured Ruve was never fully sane. The other faction had complete control. I don't believe for one minute that Jieun didn't know. She was in on it, is still in on it