THE ENDING - MAJOR SPOILERS
The new DVD of this movie has just been released. It's good to see this in widescreen, and the DVD is a very good remastering. Even more interesting are the extras, including interviews with Jill St. John and Donald Spoto (who wrote a bio about Williams).
What's interesting is how Spoto and St. John have different interpretations of the strange and very abrupt ending of the film. It's assumed that after she breaks it off with Paolo, Mrs. Stone lets a young male stalker into her apartment and he kills her. Jill St. John didn't think that's what happens to her - the young man becomes the new lover, a less spectacular (if somewhat creepy) man without the fancy trappings of a gigolo or a lady pimp in tow.
Viewing the film again, you can see St. John's point. It was obviously left open for interpretation.