There is a Arthur Earl Paetzold b. Dec 30, 1896 that filed a WWI Draft Registration Card Sept 12, 1918 in San Francisco, that states he is married. The CA San Francisco City Directory for the years 1919, 1920, 1925 has Arthur E Paetzold with spouse Isabella. There is a second 1925 and a 1927 city directory with no spouse listed. Arthur Earl Paetzold died 1985 in Monterey County.
There is a WWI Card for Arthur Stacey b. April 29, 1899 file in Oakland, Alameda County CA Sept 12, 1918 with (mother) Lucy Agnes Stacey as nearest relative. 1920 census Arthur Stacey is single in parents household in Oakland, Alameda County CA. Father William, mother Lucy A. Stacey The city directory has Arthur Stacey with no spouse listed in 1919, 1925, then a Isabelle in the year 1929 and later. Some listings have a W as a middle initial.
So look for a marriage record 1925 to 1929 and look for maiden name and first marriage name Paetzold. Also under first name Isabella and Isabelle.