I caution those of weak spirits or delicate sensibilities to turn away. The story of Fillian and Nath has an ending of cataclysmic proportion but may answer a question or two about why you do what you do at night.
Fillian has searched her entire life for satisfaction but has always been disappointed, until she finds Nath. He's been waiting for her, his other half, since before the Earth cooled. Now that they are together, they're both whole. The power of the joining of their bodies and souls changes time itself. When Fillian betrays Nath, his rage knows not the bounds of this plane of reality. He sentences Fillian to an eternity of ghostly desire. She tries night after night to find satisfaction with those who slumber, but is only left more empty.