In the book, Fan and Shu don't end up together after the war - each of them has families, and each family goes through harsh times in the "cultural revolution" because of their backgrounds.
Yuan says that her novel was inspired by the story of a friend whose mother fell in love with a Kuomintang pilot in the CACW.
The pilot later joined the Communist Party of China after the civil war ended in 1949, and flew a plane from Taiwan to the mainland.
The mother, who was born to a senior Kuomintang official, then abandoned Taiwan to escape to the mainland in 1954 to look for her beloved.
"That's the starting point of my novel," Yuan says during the book launch in Beijing.
In Yuan's book, Fan and Shu's offspring uncover their parents' story from the letters.
Another part of the novel describes the offspring's experiences during the "cultural revolution", such as being transferred to the countryside, forced labor, and encountering the twists of human nature.
This bit is largely based on Yuan's family experiences.
Yuan is the daughter of Yuan Chuanmi (1926-95), a well-known biologist at Nanjing University.
During the "cultural revolution", Yuan's family was sent to a farm in Liyang, in Jiangsu province. Yuan worked with farmers to raise pigs. Later, she was assigned to work in a factory which produced bathtubs.
"Our parents' generation experienced a lot of violence. After World War II, it was the civil war, and then waves of political movements," says Yuan.
"The violence affected people and made people nervous and distrustful of each other."
After the "cultural revolution", Yuan joined a university and studied philosophy.
In 1989, Yuan won a scholarship and went to do her PhD at the University of Hawaii.
Currently, Yuan teaches logic at Creighton University in Nebraska.
"When I write papers, I use English. When I write novels, I use Chinese, because I don't want to forget the Chinese characters," says Yuan, whose earlier novels and short stories have won literary awards.
Before Yuan finished the first draft of Hustlen Hazel in 2014, she went to Hengyang, in Hunan province, to visit one of the most important airfields of the CACW during the war.
It is now a training field for a driving school.
"Earlier generations have sacrificed a lot for peace. If we forget this and fight each other, their sacrifices will be worth nothing," says Yuan.
