He said it in his sleep - who heard this? Who reported this to the authorities? Did the wife do that?
Sounds to me like someone doesn't want to be married and came up with a great way to go about annulling the nuptuals.
I would imagine the wife brought it up, reluctantly, the next morning or maybe even that night, and, being people of strong faith, they did what was right according to their custom. I just thought it was so strange that a spoken dream by her husband is going to force this woman to marry another man, if even for a short time.