The Camel's Back - one of the stories, which entered in a collection of eleven short stories by F. Scott Fitzgerald 'Tales of the Jazz Age' (1922). 
When Perry Parkhurst decides that his long-time engagement to Betty Medill has gone on long enough, he presents her with a marriage license and an ultimatum: get married immediately or end the relationship all-together. But things don't go quite as well as Perry expected, and the two end up parting ways for good. Perry decides to drown his sorrows and soon ends up attending the same costume party as Betty, dressed in an elaborate camel costume.