"I couldn't stand how he never acted on his emotions" Wow... Rasantark would be so fucked, if he ever had to move to another duchy. In ANY other duchy it is expected of all nobles to NOT act on their emotions and anything else would be considered childish and unworthy of someone of his rank at best and straight up treachery to the duchy at worst, depending on the duchy and situation.
That being said I was both delighted and disappointed with Rozemyne's POV chapter. Great that we got one and nice to see how things are going for her, but also disappointed that the burning questions I have weren't even hinted at (due to it taking place before the time travel), of the who, why and how of her thread with Ferdinand being severed.
So far I overlooked, who I now think of as the most obvious suspect: Erwärmen. As the predecessor of Liebeskhilfe, he certainly would have the expertise to do it and he has plenty of motive to wish Ferdinand harm too, what with him even trying to kill him once, and only failing thanks to Rozemyne's interference. If Mestionora wasn't so strictly anti-violence or at least anti-killing, I wouldn't be surprised if he had taken another crack at Ferdinand.
And the 20 year setback would also serve his purpose, if he can remember the reset future events, since then he could asure that the in his eyes superior zent candidate Terza/Gervasio wins the royal selection, rather than the "ruffian's pet." I don't know him well enough to judge whether he'd do it out of sheer pettiness, but a genuine believe that it'd be better for the country might be all push he needs to do it regardless.