I watched this movie on TV back in the 70's, but it was an older movie. I believe it was in black and white. A married couple befriended a young woman (possibly a witch), this young woman develops feelings for the husband. At one point, the young woman has the wife in a place alone, puts a board on top of her and places rocks on top of the board until the wife gives the young woman her wedding ring.

I have been wondering about this movie for years!