Well, in the original, as far as I remember, the little mermaid fell in love with some human guy and had herself turned into a human girl to try to win his heart. The only problem being that, should she fail, she'd die. Which, unfortunately, happens, as the guy is seduced by some other woman, after which the mermaid turns into sea foam.
If memory serves me right.
I guess that would mean that Unknown's speaking about the Disney-fied version, in which the mermaid succeeds and marries the guy and stuff.