The story seems to go back to 19th Century Greece. Gelins are female demons, often seen in a wedding dress (or simple white gown). Sometimes she rides a horse. Her goal is to kill men. Generally, she is an evil spirit who avenged women who have had their hearts broken by men (usually men who jilt them or leave them at The Altar). She will also avenge women whose men have cheated on them. She will use her initial beautiful visage to lure her victim - at which time she will reveal her true form (so horrifying that it is unknown). Some variations of The Gelin legend has it being the spirit of a girl who had committed suicide due to being pregnant (and her intended abandoned her).