Tender Is the Night (1962)

1920s, the French Riviera: wealthy expatriate Nicole Warren's mental illness strains her marriage to psychiatrist Dick. A young American actress named Rosemary Hoyt arrives and is drawn into their circle, becoming romantically involved with the older, married Dick and disrupting the fragile balance of the group. The thought of Dick possibly being attracted to another sends Nicole on an emotional downward spiral that threatens to consume them all.