On August 4, 1916, Whitney made her debut at "The Reefs," the Payne-Whitney "cottage" in Newport, Rhode Island.

After the United States entered World War I, Quentin enlisted in the U.S. Army Air Service, and became engaged to Whitney before leaving for duty overseas.

Love letters exchanged between Flora and Quentin while he was at the front were featured in Edward Renehan's book about TR's sons, The Lion's Pride: Theodore Roosevelt and His Family in Peace and War.

[8] Before their divorce in August 1925, they had two children together: In 1927, Whitney married George Macculloch Miller III (d. 1972)[10] in Cairo, Egypt.

The marriage to "Cully" Miller was long and happy, and Whitney had two more children: She died on July 18, 1986, at Community Hospital in Glen Cove, New York.