question:  Why does Roger allude to Tristan and Isolde when confronting his wife and Cass Gordon?
context: If it only had a lease that could be broken— Roger Tennant, crossing the lawn, could see two of the three wings of the house, which radiated spoke-like from its heptagonal central portion. He could sense the restless stirring of the woman within Dana, just as he could feel the stirring toward her within himself—desire that both of them loathed because it was implanted within them by their captors. They entered the house, which had no roof, continued to move beneath a sky that glowed with light which did not come from a sun or moon. Eudalia, who had borne twin girls recently, was lying back, newly thin and dark of skin and hair, smoking a scentless cigarette. Eudalia had been a female foreman in a garment-cutting shop before being captured and brought through. He turned to Olga, broad, blonde and curiously vital, who sat perfectly still, regarding him over the pregnant swell of her dirndl-clad waist. Tennant wanted to put an encouraging hand on her shoulder, to say something that might cheer her up, for she was by far the youngest of the three female captives, barely nineteen. "But he doesn't have to—have them," objected Olga. In fact, Tennant thought, only her laughter was unpleasant, a shrill, uncontrolled burst of staccato sound that jarred him to his heels. It arrived before the meal, materializing against one of the seven walls of the roofless chamber. Tennant watched the girls as a sweet-voiced crooner began to ply an unfamiliar love lyric to a melody whose similarity to a thousand predecessors doomed it to instant success. Olga sat up straight, her pale blue eyes round with utter disbelief. Dana stood almost in the center of the room, carmine-tipped fingers clasped beneath the swell of her breasts. Somehow it brings things closer...." Their captors were utterly without a human conception of smell, living, apparently, in a world without odor at all.
output:  He knows that his wife will ultimately choose Cass Gordon over him.
options:  He knows that Cass Gordon and his wife will both be transported to the fourth dimension.  He knows that his wife will ultimately choose him over Cass Gordon.  He knows that Cass Gordon and his wife will never get to be together.  He knows that his wife will ultimately choose Cass Gordon over him.