I also checked the marriage cd and didn't see a Preston listed. I also checked the Colorado Springs City Directories for 1920-1929 and no one was listed as a spouce with him. He does have a court case in El Paso County that I found on the Colorado State Archives page. See below....
Record Type: Court Case
Name: STEWART, PRESTON W
County: El Paso
Year: 1929 Month: APR Day: 10
Origin: El Paso County District Court
Other Party: BUSINESS MEN'S ASSURANCE Co
Case Number: 17192
There is an obituary for him that I found on the Pikes Peak Library Districts webpage under genealogy in their news finder. Colorado Springs Gazette, August 7, 1941 page 4, suicide. He is buried in Evergreen Cemtery, Colorado Springs. T-051 Stewart, Preston W.; born 1886 and buried 8 August 1941.
I hope this helps.