Host Meg Wolitzer presents two stories about the course of true love, from two very different perspectives. Sigrid Nunez explores a roller-coaster romance in a small town in “This Is It,” performed by Christina Pickles, and Simon Rich offers up Stone-Age love and humor in a small cave in “I Love Girl.” It’s performed by Michael Ian Black, who also chats with Wolitzer about what he’s been reading and the tricky business of being funny.