Responses
Plot.
Because she was mad at him which is dumb as hell. Like the other 2 male leads literally abandoned Grace after the brainwashing but she wants to act like they're all just naturally assholes that's why they hurt her.
Especially after grace broke the engagement they should've immediately gone to cure him. But nahhh Ian is apparently trash and a bad person for being too weak to resist ancient dark magic that has been poisoning him for months.
After healing the holy knight and having her powers stabilize enough to heal the dragon why would she not immediately heal Ian?? She knew he would loose himself and become sick/ possibly die AND that he was highly dangerous just walking around under graces influence...