There’s a whole genre in country western/blue grass called Murder Ballads. Often its when the girl is pregnant. Often sung by the dead girl. Tom Dooley comes to mind. I think Barbara Allen is also one that goes back centuries.
A love triangle is as old as the ancients. I remember seeing the play, “Medea” (by Euripedes). Wife is discarded for a new woman and seeks revenge by killing her husband’s son. Even some modern day country music has triangle themes.. “Before He Cheats”, Goodbye Earl, Redneck Crazy”. I’m not diminishing the true tragedy of this case in any way. I guess my point is that this type of tragedy has always happened. Even in my Grandparents day.. they told of a young woman shot to death on her wedding day by a jilted ex. Jealousy (like Greed, Envy, etc) can get us in a lot of trouble.
Judy Collins: Pretty Polly. An even more mysterious situation.