Dangerous Game (1982)

During his summer vacation in Mytilene, a young and lonely small-time clerk, Kostas, becomes bewitched by a femme fatale, Anna Parisi, a thirty-five-year-old German woman married to a wealthy local businessman, Petros, who is in Athens. The two quickly become lovers and spend several days together on the island. When Petros returns to Mytilene, their encounters inevitably become estranged. But one morning, after a night of love, Anna is found dead from drowning in the sea.