Who is Sara from Ladies and Gentlemen and what is their importance?

Sara appears in the story, Ladies and Gentlemen. She is a middle aged woman, who has always regretted not sleeping with a specific man in college. Because of this, Sara quickly plans an adulterous rendezvous with this man when she runs into him years later. After speaking to a man on the airplane, however, Sara wonders which regrets will plague her more, cheating on her husband..... or once again giving up the chance to consummate a love affair with her old college crush. The reader never learns her decision, but realizes that whichever choice she makes will change her life irrevocably.