Is it really about witches?
A lot of these Euroschlock movies seem to involve witches. Anti-Christ is about the self-realization of an evil witch, and her estranged husband who finally did discover a witches cove. Melancholia is then about a good witch who is close to nature in many ways, including building twig-huts in the woods.
In Nymphomaniac the young women form a club, of kinds, where they have to tell of their exploitation of men. While they play the devil's chord on the piano?