You missed the climactic ending, leeneia, when the lady gets rescued from her vengeful husband by the silkies, and it all ends happily. Can't rush an epic story like that.

I took it we were supposed to understand there was what they'd now call a backstory, in which the lady had promised to marry the silkie, but got enticed away by Sir Odivere with his Odin Oath, which I think we were meant to understand as a kind of black magic. Perhaps this is just part of an even longer story.