Abigail (wife) died.

The evidence

• “Married, in June, 1823, Abigail Brown, daughter of Jabez Brown, of Madison Co., N. Y. ; she died in January, 1860, leaving three children— Maria, Henry (now doctor in Janesville), Eloisa. He married again, in August, 1865, Mrs.”

  1879-history-of-rock-county/27-bios-fulton.md, PDF p. 844 / book p. 848

  Butterfield, C. W., et al. The History of Rock County, Wisconsin: its early settlement, growth, development, resources, etc. Chicago: Western Historical Company, 1879. Cornell University Library via the Internet Archive, archive.org/details/cu31924028871585.

  Grade A: Found on a page of one of our sources