IMDB: https://www.imdb.com/title/tt0198825/
I've seen both a German DVD version of the movie and the re-cut and shorter English-dubbed version called "Swinging Wives". There is a scene with this man and the girl in the same room (white cupboard) in both versions, but there's no spanking shown. So either it is a publicity still (unlikely) or the picture is from a third version of this movie.