Clarissa is Susie's close friend when she's alive. But, Clarissa can't hold up to the demands of being friends with a dead person. Granted, the scene with Jack Salmon sort of attacking her in the cornfield would alienate anybody, but she didn't have to go gossip about it at school. Sheesh! Susie definitely resents this and Clarissa's failure to remember her. This bitterness comes out in Susie's unromantic description of Clarissa's sex life.