Uther and Igraine by Warwick Deeping

While Igraine slept in the abbey dormitory and dreamt of Pelleas, the man Gorlois burnt on the grid of his own passions, and found no peace for his soul.

The night sky was not a whit more black than his spirit, and his sinister cogitations were chequered ever with palpitating points of fire. The restless fever of an unfed leopard seemed his, and he was in and out of his tumbled, sleepless bed ten times before dawn. Only a boar-hound kept him company, a savage red-eyed brute whose temper suited that of his master; the dog followed Gorlois as he wandered from bed-chamber to atrium, out from the peristyles to the garden, down walks of yew and cypress, between the beds of helicryse and asphodel, over the smooth lawns clear in the eye of the moon. There was an evil thing in Gorlois's thought, a thing fit for beggarly disrelish, yet very white and lovely to look upon. He stalked like a ghost in the night, biting his lips, looking into the dark with red and eager eyes. How often he reached out in naked thought and clasped only the air. He cursed himself and the woman, honoured and abused her in one breath, grew hot and cold like a live coal played upon by a fickle wind.