Name of this vintage Danish or German forced lesbian sexploitation flick?

In 1988, I saw part of this on some cable channel (it was probably edited but looked like it might be originally hardcore). Seems like late 70's or maybe early 80's. THIS IS THE ONLY CLIP I COULD FIND of it in 30+ years! It's either Danish or German, I can't tell but sounds German. A pretty brunette wife and her older husband are in this huge mansion with maids, etc. and this stern but super-horny lesbian woman comes to stay with them. She's got her hair tied up and glasses and looks like a German schoolmistress. She's ALWAYS after the brunette wife, trying to pin her down and get into her pants. Eventually, she succeeds with the help of the old husband cooperating in their shared bathtub. It's really very erotic, the blonde glasses woman beds at least one of the female maids and someone walks in while she's having the maid go down on her. IF YOU KNOW THIS FILM PLEASE POST!