Okay wait. Do you want to hear the one I based it off of first :0 It's based on a story a father told his son :0
A long, long time ago, the Mermaid Princess fell in love with a human prince. But for years, her love went unrequited. Before long, she was old and decrepit, all alone even on the day of her death. The poor, poor Princess of the Sea Kingdom. Who'd ever want to become an ugly woman like her? I am yours, even in death. The story later turns out was about a girl that was abused and cut herself. The story was written from a child's perspective, confusing the cuts with gills and assuming that the girl was a beautiful mermaid.
No, it was a storybook a father once told his son to get him to sleep. There are many from this guy. Near impossible to find if you don't know how to look for it.
I have no idea...but what happened (read his biography) was that he ended up writing 7 stories for his son, but his son ended up dying, and he wrote his last story before he died.
Sorry if that scares you, I'm just really into sad stories. I usually end up writing some pretty sad stuff myself, but The Mermaid Princess has some sort of beauty to it. The ending just seems... Beautiful. It gives me the feeling of what love can actually do.