“The following is a work of fiction. Any resemblance to persons living or dead is purely coincidental. Especially you, Jenny Beckman. Bitch.” This “author’s note” sets the sardonically charming tone of this wry riff on the perennial “boy-meets-girl” saga. Skittish Zooey Deschanel is Summer, Joseph Gordon-Levitt her suitor Tom. He believes in true love. She does not. Debut director Marc Webb does a fine job, eliciting charming performances.