The Virtuous Bigamist (1956)

Original title: Era di venerdì 17

The Provence, somewhere in the 1950's. Paul Verdier, traveling salesman, leaves his home and his quarrelsome wife for his weekly round. On the train he meets a young woman, Marie, who looks a little lost. No wonder. Marie is pregnant but lacks the customary husband. She's returning to her village but is not exactly looking forward to the confrontation with her parents and the villagers, all pretty conservative people. After getting to know Paul a little better (for which there is ample time during the trip by train and bus) Marie decides to ask Paul to act as her husband, just to allay the suspicions of her family. After some hesitating Paul accepts, charmed by the girl and unaware of the complications such is bound to cause to his own life.