Pokémon - Image #672,540

Marries someone else, huh?

That is all the more fitting, because, in the original story, if she didn't get 'true love's kiss', then she would die and become sea foam.

The mermaid was offered a knife by others of her kin to murder the prince in order to become a mermaid again. Instead, the mermaid accepted her fate, died, and became a wind spirit which, through good works, gained the opportunity to go to heaven.