In 1903, Boyce purchased a four-story mansion on in Ottawa, Illinois, which became the center of his family and social activities. Thereafter, he showed little interest in Chicago and its social activities; he would only go there on business. Boyce and Mary led increasingly separate lives and eventually divorced, which was reported on the front page of the "Chicago Tribune" because of the prominence he had attained by that time. The divorce was finalized in a Campbell County, South Dakota court in September 1908; his wife's property settlement was close to $1 million (USD).