The Narrator, uncouth beyond belief, a social reject, an unlicked cub, does by some miracle have an affair with large and bouncing Susan. For a man who has been rejected all his life he seems to know the ropes rather too well. French's sex scenes are never pornographic. With Susan the Narrator feels normal, almost. But for her he is an aberration soon to become an embarrassment. She reverts to type and moves in with a suave operator with a glitzy flat near Primrose Hill.
This final rejection sends her ex into an anti-evolutionary leap and he is soon a monkey scrabbling about on Primrose Hill preparing to spy on them. He's eventually taken in as the family pet. And watches their love scenes eating bananas and gibbering the while.
This is the darkest pit of the jealous imagination: voyeuristic of all that gives the most intense pain. He is condemned to cavort and charm or else he'll be sent off to the vivisectionist. Things go sour: 'Do you know that feeling when the little things in your life seem to be going wrong? A cake gets baked with what must have been salt rather than sugar. Somehow the purple T-shirt goes in with the rest of the wash an absolutely everything goes a shade of light blue. . .' He observes their intimacies, such as her picking her nose, until he begins to despise her pathetic humanity and stops caring.
As a metaphor for jealousy this Beauty and the Beast in reverse has a certain shuddering power.