It was when she was young. That’s true, she has no reason to think her father is worried about her, but he only told her to not get sick. And yet, she deduced something else from it when it was just a simple sentence like the other misunderstandings (they often start from a simple sentence from...
her father gives her signs of affection but she prefers to see the bad side of his words (since when "don't be sick" means "don't be sick because you have to marry the prince"..)