Then what this means is Regis is just a stupid daughter-con that was so bad at expressing himself that he accidentally made her think he hated her.
then the emperor (?) framed her for the poisoning and wanted her jailed, which forced Regis to put her in the eternal timeout room, maybe to make it so she was safe from anyone but the royal family. At this point he decides to overthrow the emperor. Again his dogshit communication skills fail him and he gives no indication he wants her to do anything except stay there forever, but the dagger was for self-defense, and "endure it" meant "wait for me sweetie daddy has to take out the trash".
the crown prince comes to get her to safety (?) but she thinks he's going to torture her and kills herself??? What kind of tragic fucking misunderstanding...