In the summer of 1919, after less than a year of courtship, Zelda Sayre broke up with the 22-year-old Fitzgerald. After a summer of heavy alcohol use, he returned to St. Paul, Minnesota, where his family lived, to complete the novel, hoping that if he became a successful novelist he could win Zelda back. While at Princeton (notably in University Cottage Club's library), Fitzgerald had written an unpublished novel, "The Romantic Egotist", and ultimately 80 pages of the typescript of this earlier work ended up in This Side of Paradise.
On September 4, 1919, Fitzgerald gave the manuscript to his friend Shane Leslie to deliver to Maxwell Perkins, an editor at Charles Scribner's Sons in New York. The book was nearly rejected by the editors at Scribners, but Perkins insisted, and on September 16 it was officially accepted. Fitzgerald begged for early publication—convinced that he would become a celebrity and impress Zelda—but was told that the novel would have to wait until the spring. Nevertheless, upon the acceptance of his novel for publication he went and visited Zelda and they resumed their courtship. His success imminent, she agreed to marry him.