Banks of the Ohio Close-Ups
Willie pulls a knife and forces her to fall into the water where she drowns. You can she her body floating in the water on the far left side.
"I asked my love to take a walk- Just a walk a little way" The happy couple before he proposes marriage and she turns him down. Some suggest that she tells him she is too young to marry (Laws).
In this scene he calmly sings the song as he watches her body float down.