If your relative had a marriage at the end of their life that did not last long (due to their age) and may have resulted in no children, have you researched that marriage and spouse completely?
Depending on the place and time period, that marriage record may tell you more about your ancestor than their earlier marriage record. Your ancestor may have actually known the spouse for decades before the marriage (or at least been aware of them) and the spouse’s migration path may help you learn more about your own ancestor.
Family heirlooms, family Bibles, etc. may have passed to the family of this final, short-term spouse. In the case of female ancestors in the United States and many other countries, knowing the last name of that last spouse is crucial to finding out information about the female’s death, estate settlement, etc.
That spouse your ancestor had at the very end of their life could be crucial to locating more about them. Your ancestor apparently didn’t ignore them. You shouldn’t either.