Le Garde du corps (The Bodyguard) (1984)

Barbara (Jane Birkin) marries Julien (Sami Frey) a charming and sexy man. Barbara's old flame Paul (Gérard Jugnot) is highly suspicious of Julien. It seems Julien's previous two wives died under dubious circumstances and he collected a wad of insurance money as a result. Paul cannot ignore his misgivings, and so he follows Barbara and Julien to Morocco on their honeymoon, intent on preventing any harm to the woman he still loves.