Dropped from Heaven(1946)

Gaby, the singer of the "Raymond's Jazz" band, leads Maurice, one of the musicians, to believe that, following a night he spent with her in the hay, he is the father of her child. In fact, the baby is neither his nor hers. He is the son of Madeleine, a young war widow who has entrusted him to her friend Gaby until she is allotted a flat. One day, Maurice happens to meet Madeleine and falls in love with her but he does not dare to confess his "paternity" to her. Fortunately the misunderstanding is clarified and Maurice can at the same time marry Madeleine and adopt her kid.