Power Sex Couples(1977)

Original title: Couples complices

Jacques is summoned by his boss to transfer to Paris. Very soon he discovers and enjoys the hidden joys of the city. He would like to share it with his wife, who waits patiently every week-end, but he soon discovers Paris is much more than a honeymooner's paradise. She discovered his sexuality was a bit more exotic than she was accustomed to. But she doesn't fret; the prospect actually turns her on enough that she decided to join in on the fun.