A Mistress for the Summer (1960)

Original title: Une fille pour l'été

Philippe, a little known artist, has a mistress, Viviane, a woman he does not love. When he learns the bailiffs are about to seize his paintings, Philippe decides to leave alone for the French Riviera and spend, as he regularly does, comfortable and carefree holidays in the luxurious villa of his friend Paule. But, on his way, he meets Manette, a beautiful but poor girl to whom he offers to become his companion for the Summer. Manette accepts the strange deal in exchange for bed and board. As Philippe always comes in the company of his mistress of the time, the presence of Manette does not pose a problem. But the young woman soon feels ill-at-ease in such a dubious environment. moreover, she realizes that she is falling in love with Philippe, who might not be so cynical as he wants to appear... - Written by Guy Bellinger on IMDB