Father Knows Best (1954)

Season 3: Episode 33

Henry Pruett, a traveling salesman on tour, accidentally knocks on the door of Margaret: she, Jim and Henry attended college together and he was a promising man back then - on his way to become a doctor. But all he is now is the salesman (and a bad one too) and that's embarrassing for him and he decides to keep it a secret. But Margaret and Jim find out about this anyway.