De profesión, sus labores Colonna sonora (1970) OST

While Ana and Juan are a happy couple satisfied with their eight years of married life, their best friends María José and Federico have not achieved the desired balance in their marriage, so Ana and Juan's happiness provokes their friends' envy. María José and Clara, Ana's "good" friends, try by all means to make Ana believe that her husband is capable of cheating on her if the opportunity arises.