Mi Mujer no es mi señora (1978)

Juan Carlos, a businessman, falls in love with a woman much younger than him, and ends up marrying her. Juan Carlos' mother-in-law, following an incident with him, tells him a fabricated story: that the father of her daughter is a stranger, with whom she had sex in the car of a train. Coincidentally, this situation had happened to Juan Carlos many years ago, and now, with the doubts that his wife is his daughter, he does not even want to approach her on his wedding night.