I present to you, a lesson that has been forgotten that our fathers understood:
Beware women with false tongues promising all things to get men to marry them.
Such things we enshrined in folk songs like Herr Mannelig.
I suspect that the song was written not to refer to "trolls" as such but pagans as the male response is that he might if she were a Christian woman.
Songs like this help encourage men to support the culture and keep men from listening to their urges.