Your ancestor had relationships that did not generate records. It’s obvious when one thinks about it, but often something that we forget.
A relative of mine had a short-term boyfriend in the state of Iowa in the late 1870s that resulted in a pregnancy. She never married the father of the child. I only know his name because her subsequent marriage to Civil War veteran resulted in her applying for a widow’s pension where she mentioned the previous relationship.
Another relative was “married” in the 1850s for less than a few months to a man who was temporarily guardian for her minor children. I suspect she was married to him (or acted like she was) because she signs his last name to some documents involving her first husband’s estate.
I just got lucky I was able to locate information on these relationships and it makes me wonder how many relationships leave no record at all.