In Cold Blood

Bobby Rupp was jealous of Nancy's friend Sue.

"Until Nancy's death he had not appreciated Sue, never felt altogether comfortable with her. She was too different - took seriously things that even girls ought not to take very seriously: paintings, poems, the music she played on the piano. And, of course, he was jealous of her; her position in Nancy's esteem, though of another order, had been at least equal to his."