If indeed it was "Appalachian" in orogin then it could easily have pre-17th c. roots in Irish or Scottish songs and the theme is certainly not unlike many of those; but I do not recall hearing anything I could identify as an antecedent in tune.
Kendall's rendition is beautiful.
To my mind there is no question that there were two women, one of whom is ineligible for the affections of the gentleman in question, but who loves him dearly from afar -- and the other of whom gets the man but who is cold. This is the kind of tale that fired the Romantic era, I imagine. Anyway, it seems straightforward to me.