Not sure if this is any connection, but since the surnames are the same, maybe it will provide a clue. Lewis Dow b. 4 Sep 1867, Dover ME m. 9 Nov 1903, Lillian G. Mitchell b. Pasadena CA, 15 Jan 1887. Lillian was the daughter of Charles W. Mitchell and Rachel Taggart.
What location are the markers you mention? There are many ELiza Dows, and my information does not include date or location in the index. Although I have nothing on an Eliza Dow marrying a Taggart, if you give me a location to go with the dates you gave, I will see if anything looks like a possible match.