He wasn't manipulating the entire time, especially towards the third condition it was clear that he knew that Rhyse was wicked but he was still so red-flag obsessed with her that he wanted to be a part of her schemes. Then when the real Rhyse comes back he immediately realized and was disappointed that "his" Rhyse was gone and becomes obsessed with finding that versions of her again.
I think he really did deserve the ending he got, because even without the world controlling his actions he decided to abandon the 2nd chance he got from his parents in order to find "his" Rhyse.
Well I guess I just don't pity him for that. After the influence of the book stopped he could have chosen to love the other not as twisted Rhyse and he could have chosen to stay at the borders and show his dad that he deserves to be the duke. But instead he chose of his own accord to leave the world to pursue the wicked Rhyse.
Even if I take into account that it might be hard to withdraw from the book's influence, I don't see why he's pityful for acting like that and being a red flagged obsessive guy. And the fact that he turns violent in the end just really shows his true colors ┑( ̄Д  ̄)┍

perfect ending but i would say, it's a bit unfair for Cliff side. He was manipulated, and even through he was free from the author, how was he supposed to know? I feel like the best would be meeting someone in the new world, or just remain in his original world but single.