Matt Groening first conceived Marge and the rest of the Simpson family in 1986 in the lobby of producer James L. Brooks' office. Groening had been called to pitch a series of animated shorts for The Tracey Ullman Show, and had intended to present an adaptation of his Life in Hell comic strip. When he realized that animating Life in Hell would require him to rescind publication rights, Groening decided to go in another direction and hurriedly sketched out his version of a dysfunctional family, naming the characters after members of his own family. Marge was named after Groening's mother Margaret "Marge" Groening, who has said she bears little similarity to the character, stating, "It's really weird to have people think you're a cartoon." Marge's beehive hairstyle was inspired by the titular Bride in Bride of Frankenstein and the style that Margaret Groening wore during the 1960s, although her hair was never blue.  Marge debuted with the rest of the Simpson family on April 19, 1987, in The Tracey Ullman Show short "Good Night". In 1989, the shorts were adapted into The Simpsons, a half-hour series airing on the Fox Network. Marge and the Simpson family remained the main characters on this new show.  Matt Groening believes that episodes featuring Marge are among the most difficult episodes to write. Bill Oakley believes that the "junior" writers are usually given Marge episodes because he and writing partner Josh Weinstein were given several to write during their first season. During the third season of the show, most of the writers focused on Bart and Homer, so David M. Stern decided to write a Marge episode, which became "Homer Alone" (season three, 1992). He felt that they could achieve a "deeper vein" of comedy in an episode where Marge has a nervous breakdown, and James L. Brooks quickly approved.

Answer this question "What makes them difficult to write?" by extracting the answer from the text above.
During the third season of the show, most of the writers focused on Bart and Homer, so David M. Stern decided to write a Marge episode,