Well, there are several love ballads of the "broken token" variety... man goes off to sea/war/longhunting/whatever for three/five/seven years, comes back to find sweetheart doesn't recognize him till he pulls out the "token," usually a ring or a pendant or some kind of mojo/good luck charm, then she knows it's him.

Twenty gazillion versions of woman running off with gypsies.

Many, many lover's ghost ballads. One of my faves is "The Nightingale," where the girl's parents have the boy pressed into service because he isn't good enough for her. Ship wrecks, he dies, ghost comes to tell her what happens. Or else lover is murdered by girl's brothers, or some such. I guess these are sort of murder ballads, too, in a way.

I like night visiting songs: who's that at my window? Tis I, tis I, arise and let me in. Very romantic!

Murder ballads? Well, I'm leaving to get a haircut in five minutes. I may have to come back to this.