Edgar A. Poe, "Eleonora," in The Gift: A Christmas and New Year's Annual.

        The protagonist describes, in dream-like language, his love affair with his cousin, Eleonora, in the Valley of the Many-Colored Grass.  His beloved senses she is dying, and he promises to be faithful to their love forever.  After her death, her spirit comes to him in the night and whispers to him, assured of his faithful promise-keeping.  Slowly he grows dissatisfied with life in the Valley of the Many-Colored Grass, and leaves it.  He discovers a new love, Ermengarde.  The whispering voice comes to him again at night and assures him that "in taking to thy passionate her who is Ermengarde, thou art absolved, for reasons which shall be made known to thee in Heaven, of thy vows unto Eleonora.'"