Holiday Affair (1949) on Netflix

Connie Ennis is a widow with a young son, Timmy, who works as a comparison shopper. After she buys - and then returns - an expensive model train set, store salesman Steve Mason should report her to his superiors. He decides to give her a break but gets fired for his trouble. He likes Connie but she has been dating Carl Davis for two years and he's waiting for her answer to his marriage proposal. Timmy certainly takes a liking to Steve and Connie isn't quite sure what she thinks of him. In the end, she realizes the choice she has to make and takes a leap of faith.