This song has many names, including Sweet William, Sweet Willie, The Lost Lover, Down by the River Side, The Sailor Sweetheart, The Sailor and His Bride, Moment's River Side, The Forsaken Lover, The Sailor Boy, The Faithful Sailor Boy, etc. (Cox, Randolph,Brown).
The song is difficult to look up because the titles overlap with those of other (unrelated and related) songs.
There are others that speak of a lover's black curls, etc.
They all seem to vary around "The Sailor's Sweetheart, given above.
Scathy, I could give you other Appalachian-Ozark versions if you want them.