The only time I've ever seen this movie the film quality was very poor. That was in the 70s or so. I remember when it was playing the drive-ins fairly frequently and that was the late 50s and early 60s. As Barbara Payton and James Craig were unknown to me then I figured it was because of Guy Madison who we kids all knew from Wild Bill Hickock..
You can't say it a love triangle because there's a fourth player in the mix-the war. Everyone is committed to their side which puts their feelings on the back burner. Since they are in the South you can understand the impact is greater on the couple than their Northern friend who is still a soldier and has his duty to do. That bit with the piano wire is a novel idea I've never seen in a film before.
I wish the prints were better too. It might show the movie is better than it's given credit for.
I think you're right. It may explain why I had a more favorable reaction to the film than the OP (Ian), since I had viewed a restored print.
Interesting the film was still being shown in theaters ten years after it had been produced. It probably also had airings on late-night television.