It is if the ml poisoned him
True but obviously he wouldn’t
I think it's ok due to emotional stress and old age. He got betrayed by his beloved grandson and basically need to punished him. I mean he was selfish enough to but Erin on such difficult and painful situation. Her being married just to be a stabilizer for the grandsons magical whatever and left alone to face the humiliation of their marriage so the king truly love that grandson of a bastard but then at end it was all for nothing.
I don’t like how they instantly made the king sick once the ml became crown prince that’s very unrealistic.