He married Josephine Maria McDougal on September 28, 1861, in Poughkeepsie, New York. His father presided over the marriage ceremony. McDougal was born on June 16, 1839, in Indianapolis, Indiana, and was the daughter of Brigadier General Charles McDougall, a surgeon in the Army. Buel had two children. His daughter, Josephine Maria Buel, was born on February 13, 1866; she later changed her name to Violet McDougal. His son, David Hillhouse Buel, was born on June 19, 1862,[1] and became a Jesuit priest and the president of Georgetown University, before converting and becoming an Episcopal minister.[3]
On July 22, 1870, Buel attended a party at the house of Brigadier General Samuel D. Sturgis.[7] While exiting his carriage in which he was returned from the party, he was shot and killed by a soldier,[1] whom he had imprisoned in the guardhouse for desertion.[2] His widow married Buel's uncle, Oliver Prince Buel, on December 1, 1875, at Jefferson Barracks in Missouri.[1]