Scandinavian tales and creatures

Once, a young man was out hunting when he spotted three swans landing by a lake. The swans suddenly cast off their bird guises and became three beautiful young women instead, and they waded out into the water to bathe. Enthralled by their beauty, the young man snuck forward and stole one of the guises, which to him looked like a feathered white cape. When the women had finished bathing two of them changed back to swans and flew away while the third cried and begged to have her cape back. The man ignored her pleas and took her back to his home to marry her. For seven years they lived together, but on the evening of their seventh wedding anniversary, he told the her about her white cape and showed it to her once again. The moment she touched it she turned back into a swan and flew out the window, leaving the man forever.