The Snow Maiden is a Russian tale that was set to music first by Tchaikovsky, then made into an opera by Rimsky-Korsakoff.
The tale itself is along the veins of the stories of seals, selkies, mermaids, or any other inhuman girl who lives on earth and has trouble with her love life. The Snow Maiden is the daughter of Spring Beauty and Grandfather Frost, and wants to go live with the villagers. The man she loves (Lel) loves another, while she does not love the man who loves her, (Mizgir,) which makes Mizgir's former lover, Kupava, jealous...but she ends up with Lel.
Mizgir still loves the Snow Maiden, and after seeing how happy Lel and Kupava are, the Snow Maiden decided she wants to truly be able to love (apparantly her affection for Lel before didn't cut it.) Yet as the Snow Maiden declares her love, a ray of sunlight appears, and she melts. Everyone is horrified, but it ends the fifteen year long winter under which the villagers had suffered.
The moral of all these stories appears to be that inhuman girls and mortal men can never stay together. Whether these were propogated by men who had been rejected and were feeling sorry for themselves, or women who hated the thought of being chained down, or by people who truly believed in superhuman creatures who were prone to romantic longings but did not belong with mortals, I don't know; but this type of tale is found all across Europe.
The excerpt above is from Rimsky-Korsakoff's opera. Below is from Tchaikovsky's incidental music to the same tale. This movement, Dance of the Tumblers, is very popular: