Faery Marriages
Some tales of faery brides who married mortals seem to have earthly verification.
The Gwragedd Annwn are beautiful, Welsh, fair-haired faery women, the same size as humans, living in underwater palaces in lakes close to the Black Mountains. These lake maidens have, on occasion—according to folk lore of the area—taken human husbands, though they rarely stayed with them. Some local families still claim fey heritage.
One Lady of the Lake in Llyn y Fan Fach is, however, said to actually be the fairy ancestor of an unbroken line of Welsh healers and physicians. Even more unusual, this faery legend can be dated. Around 1230, records tell that a young farmer saw three beautiful women dancing on the shore. The most beautiful agreed to be his wife and her father, the king of the lake faeries, came from under the lake to bestow a dowry of fairy cattle. However, the faery king imposed a number of conditions on his daughter staying with her mortal husband. One condition was that she should never be touched with iron, another that she should not be made to go to church, and a third that if her husband struck her three times she and her dowry would return to the lake.
The couple had three sons, but the farmer broke his bargain by striking his faery wife three times (though according to less enlightened male folk tellers, the poor husband only tapped the faery lightly and for good reason). A faery bargain being a faery bargain, off went the cattle and faery maiden, though she did return to teach her sons knowledge of herbs and healing. They became the Physicians of Myddfai, healers to the Welsh kings. When they died, they left a medical treatise, copies of which exist today. I believe there is one in Cardiff Castle Museum.