I watched this movie on Israel Channel 2, sometime around 1995. It was not in English language (maybe dubbed). Seeing all the nudity and off-screen sex scenes, it was definitely not a US film.
Film starts with a glasses wearing scrawny looking guy who visits a friend or someone he knows. The latter was always wearing nothing but a robe and panties. Had a huge collection of nude catalogues and sex position materials. He was probably a man that gets paid to have sex with women. Soon, he gets picked by ambulance and hands over his panties to the first guy.
Fun starts here: I do not know how, but he runs into a (homeless?) girl. She moved in. Seduces him. One scene in particular she spat milk over her own body. Milk flowed down and she opened her robe to reveal she was waearing nothing (breasts & nipples). Man started licking milk off her body. Next scene they are both inside shower behind frosted glass.
They had many sex encounters. Then got into an argument where she left/or got thrown out. Few days later she comes back as she had no where else to go I think. He let her in, yet keep on humiliating her by having fun with other girls when she is around and force her to serve as a maid.
Near the end the man tricks her by leaving his seat inside the airplane and let her fly alone.