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Well, the frog indeed turns into a handsome prince, but the story is not about a curse. It is about the love of a mother, the love between man and woman, and most of all it is about reincarnation.
Reincarnation has a very close relationship with karma. How and in what form you are reborn to the world depends on your karma, as a result of your actions and attitude in your previous life.
So the Frog Dance is a fairytale about a couple who have no children.
"... One day, the wife goes to the forest to collect some firewood. After walking for several hours she feels thirsty, and takes a coconut shell to fill it with water to drink. Returning to the village she encounters a big frog on the way and she suddenly falls pregnant.