Am just now getting back into the hobby after burning myself out a few years ago. Have copies of some wonderful books of newspaper extracts that Mary McRoberts did in 1991. They cover the period 1859-1900 and one is : "Boulder County, Colorado / Marriages, Anniversaries, Divorces, Births and Birthdays / 1859-1900 / Newspaper Abstracts / Mary McRoberts / Boulder, Co/ July 1991" And the other is : "Boulder County, Colorado / Deaths and the Insane / 1859-1900 / Newspaper Abstracts / Mary McRoberts / Boulder, Co / July 1991"
I trust her extracts but beware of my typing. Hope I'm accurate. Found the following entry -
1. Divorces - "Stanley, Mrs. F.D. is to begin divorce proceedings soon. Married about 2 months ago in Kansas City. Moved to Boulder about 6 weeks ago. She was Mrs. Flethcher, a widow, when she married Mr. Stanley. He, she found out, is a drunk and brutal. She called her son-in-law, Dr. Clark of Ft. Collins, to come get her which he did. (HW 8 Dec 1886:5)" [HW=Boulder County Herald].
This was the only listing. Didn't find any marriage or birth notices. Not all papers survived from that period. And not all births got typed up. But my suspicion would be that the IGI entry was a guess and that Larimer County (Ft Collins) may be where the marriage etc took place.
Sorry I didn't find more and good luck. David Knowles