The King of Elfland's Daughter by Lord Dunsany

The lord of Erl is told by the parliament of his people that they want to be ruled by a magic lord. Obeying the immemorial custom, the lord sends his son Alveric to fetch the King of Elfland's daughter, Lirazel, to be his bride. He makes his way to Elfland, where time passes at a rate far slower than the real world, and wins her. They return to Erl and have a son, but in the manner of fairy brides of folklore, she fits uneasily with his people. She returns to the waiting arms of her father in Elfland, and her lovesick husband goes searching for her, abandoning the kingdom of Erl and wandering in a now-hopeless quest. However, Lirazel becomes lonesome for her mortal husband and son. Seeing that she is unhappy, the King of Elfland uses a powerful magic to engulf the land of Erl.