Treehouse Books & Melanie Voland 
The Story of Undine: Traditional Mermaid Folk Stories Collection [EPUB ebook] 

A changeling water spirit gains a soul, when she falls in love with a human being…
But if a human rejects the love of one of her kind, she will disappear…
And if he betrays her, he will die…
A romantic, tragic, supernatural story that may only be suitable for kids at higher middle grade age, young adults and anyone else.
This is book 12 in the Traditional Mermaid Folk Stories Collection.