I did a study,for my own interest, on the "Butcher's Boy" songs. Not the first by a long shot of course. I approached the study as a singer first and scholar second, trusting instinct at times. I came up with about 50 that seemed to be related, but I'm still finding them. There are a great many that are very lovely and I sing about 10 of them. The earliest I found that fitted my criteria was a broadside Ballad called "Arthur's seat shall be my Bed" - from c.1776. Many seem to have related melodies but several are quite distinct. A lot of songs have verses that are floating ones common to many love-story ballads but the critria I came up with (and tried to stick to) were:
1. Young girl falls in love with young man who leaves her pregnant. He often takes another on his knee in the local tavern/alehouse and tells her things he won't tell the deserted maid.
2. She wishes her baby was born and she was dead. The lines "once I wore my apron low" are often used.
3. She plans her burial.
4. She kills herself (usually by hanging and usually leaving a note) I also included some varients where the song ends just before her death.
"Careless Love" seems to fit in too but the tables are turned and the maid plans to shoot her former lover.
I know a lot of this has already been said but I post my thoughts in the hope that they may add something.