The original story of the little mermaid is that she must kill the prince in order to be human, and in the end, she loves him too much and kills herself instead.
BECAUSE EDVARD WOULDN’T FUCKING LOVE HIM!
Actually in the original story the witch cuts out her tongue as payment for being human, and she must get the Prince to marry her or else she will die. On the Prince’s wedding night, she finds out her sister’s gave the evil sea witch their hair as payment for a knife she must plunge into the heart of the Prince before sunrise the next day to become a mermaid again. Because of her good deeds, she does not die but instead goes to the spirit world taken under wing by the daughters of the air who tell her that she can indeed obtain a mortal soul (the only known way for mermaids to do this is to have a human fall in love with them) in 300 years if she continues doing good deeds.