From The Movie Snob:

Intimate Strangers (B-) (French w/subtitles). William Faber is a middle-aged, never-married tax attorney in Paris. He is a quiet, unassuming fellow who lives in the same apartment, behind his office, where he grew up as a child. One day, however, an attractive woman named Anna comes to his office without an appointment, tells him briefly about her marital difficulties, and leaves abruptly after making a follow-up appointment. Faber belatedly realizes that she mistook him for the psychiatrist whose office is down the hall on the same floor. Anna realizes her mistake almost as quickly, but she nevertheless continues to see Faber and tell him ever more intimate details about her marital and psychological issues. I guess the idea was to build up some romantic suspense, as Faber becomes obsessed with Anna even while starting to doubt the truth of the lurid things she tells him. I thought it was an interesting premise, but the execution was somehow lacking. Although I think we're supposed to wonder how much of Anna's stories are fabrications or fantasies, the director actually dispels a lot of the mystery by showing stuff right on screen that would have been better left unshown, or at least ambiguous. At least in my humble opinion.