In the old tales, they never explain anything properly, but they also never tell you why.
Follow instructions, don't elaborate, don't stray outside the lines.
A prince became a fox and roamed wild, set as guardian against any who would come seeking his sister. He had listened once but not followed instructions. He wasn't entirely certain why he continued to bother with this new prince who listened but never quite kept all the rules.
But finally, he asked, "Cut off my head and my paws." Free me, he thought.
The rules of his curse didn't say he could explain why.