I did see the other Nathaniel MacFarland on a Census who married Ida and don't think he's your ancestor.
I didn't find your Nathaniel S. M. McFarland's marriage online but didn't expect to because early marriage licenses were originated and filed at the Town Clerk's office. You can contact the Town Clerk, www.townofbroadalbin.org/Town_Clerk.htm
and ask about a search for their marriage license.
Broadalbin also has a Historian and library. The historian might be of help if the Town Clerk isn't. Also it's possible that the Library has a listed of early marriages. Successful Searching!