Just happened to be reading Bocaccio's Decameron, and the Eighth story, fourth night, struck and eerily familiar chord--

A young man (but sickly) from a wealthy family and the daughter of a tailor grow up in love with each other--his mother gets the executors of her husbands fortune to send the young man to Paris,on business (but really just to get him away from the girl).

He is there for several years, all the time pining away and thinking of nothing but the girl--.

He finally goes home, only to find her married to a tentmaker. He walks up and down in front of her house, but she either doesn't recognize him or pretends not to recognize him.

He sneaks into the house and when the husband falls asleep, he pops out and declares his love. She replies that he is the one who left and never wrote, so she married someone else. She then says that she intends to forget about him, and asks him to leave.

He realizes his love letters never reached her,and that, since she intends to forget him, he has no reason to continue living, and he dies. She is upset because, even though she is innocent, it looks pretty bad, what with another man being dead in a bed in her house--She decides to wake her husband and tell him the story, but pretend that it happened to someone else-- He laughs, and says that, of course, the woman is not to blame, at which point she says that she is glad thinks so,and shows him the dead man.

He picks the guy up and carries him back home, where he surreptitiously dumps him on the door step and takes off--Whereupon the body is discovered, and everyone is bewildered and scandalixed--

The couple are afraid that gossip might connect them with the death, so they disguise themselves, and go the the church to hear what people are saying. When she sees the body, she is suddenly overcome with long suppressed love, falls on the body, and dies--

At which point, the husband stands up, confesses the whole story, the assembled crowd agrees that it is all a tragic affair, and the two unfullfilled lovers are buried together--

The Decameron was written in about 1350, and there was a popular English translation published(I believe) before 1650, so it is not so far fetched to imagine that it was a source for balladeers--

At any rate, the whole text of the Decameron is here--search for the name "Silvestra" which is the name of the Barbara Allen-like maiden, and it will take you to the first line of the story(this is one of the greatest works of Western Literature, so if you haven't read it, it's worth checking outDecameron