An older foreign film, most likely 1970s/early 80s, I say most likely French because I saw it around the time I watched Betty Blue, and it is similar.
Man is married/engaged I believe but cannot let an old lover go (or maybe they have no past) the other woman is long dark haired and very attractive, she lives up on a rocky cliff nearby the man and his wife, the man sneaks up there and they have passionate sex often, I distinctly remember the woman has hairy armpits. The rocky cliff is by the ocean I think? I believe the wife eventually finds out, I can’t remember what happened. I only remember there being a lot of sex between the man and his lover, mostly in her little hut/house and I believe it’s on a rock inside of the house, again, distinct hairy armpits. Please give me your ideas and I’ll look them up- once I see a scene I will know if it’s it or not. Thanks!