A Dear John Letter
"A Dear John Letter", or "Dear John" is the name of a popular country music song. It was popularized by Ferlin Husky and Jean Shepard, and was a crossover country-pop hit in 1953.
The song played on the concept of a Dear John letter while referencing the United States' involvement in the Korean War. Here, a young woman, whose boyfriend John was stationed in Korea, writes stating that she is breaking off the relationship. To add to the heartbreak: She is marrying John's brother, Don, and wants her photograph back (because — according to the lyrics — Don wants it now).