Maybe I'm either painfully naive or worldly wise, but the meaning of the elevation of the young lady's apron and the guy's ducking out on her because of it has always seemed crystal clear to me.

She'e preggers, he got her that way, and he's shirking his responsibilty.

Claire, the lovely girl I was going with back in 1951-52 and who was primarily responsible for getting me interested in folk music in the first place had an interesting and revealing verse that followed the one about the height of the young lady's apron:

You pass my door, you pass my gate,
You pass my door, you pass my gate,
You pass my door, you pass my gate,
But you won't get by my thirty-eight!

Don Firth