Another tale, "Lord Peter," involves one of the stranger motifs in fairy tales: the potential bridegroom or bride--while in another shape--commands the significant other to perform a violent act on the bridegroom or bride. In "Lord Peter," the cat who helps Peter threatens to "to claw [Peter's] eyes out if he did not...cut its head off."
"The Frog Prince" falls under this description to an extent since the frog transforms once the princess throws it against the wall.
The frog prince doesn't ask for the violent treatment though he does appear to deliberately provoke it. The oddity of the above tale and others like it is the violence perpetuated on the lover doesn't raise any red flags.
It should. All the rationales in the world don't overwhelm evidence. A person who uses death as a solution to non-violent circumstances is sending up all kinds of sociopathic signals. Dr. Kevorkian was a serial killer with a social mandate, and any family member who delivered a loved one to his "tender" care was exhibiting a bizarre level of irresponsibility.
But at least the loved one was, ya know, dead at the end.
Yet in the aforementioned tales, the loved one is restored to the preferred form. The response is, "Oh, you're still alive. I love you so much despite that terrible thing I did at your request--hey, let's get married!"
Personally, I think the cat-princess's response should have been, "Thanks. But I'm going to marry someone who can't be pressured into cutting off my head when the going gets tough. I'd never sleep easy beside you."