The answer is "She loses her enchantment when removed from her woodland home". The author is enamored with the maiden as indicated by the line "The lover watched his graceful maid" and "Nor knew her beauty's best attire, Was woven still by the snow-white choir". However once removed from her previous environment her enchantment is lost as indicated by the verse "The gay enchantment was undone" or in others words the lovers happy enchantment was no more.