The Comfort of Strangers (1990)

IMDB
Genre : https://www.imdb.com/title/tt0099292/
TRAILER
Director : Paul Schrader
Stars : Christopher Walken, Rupert Everett, Natasha Richardson, Helen Mirren
Plot : Colin and Mary retreat to Venice to work on their relationship, but an encounter with lyrical local bar owner Robert and his odd, sexually frank wife Caroline leads them into a world of intrigue where their darkest desires are in reach.