Never Say Goodbye (1946)

Phil and Ellen Gayley have been divorced for a year, and their 7-year old daughter, Flip, is very unhappy that her parents are not together. Flip starts a correspondence with a Marine, sending a picture of her beautiful mother as the author of Flip's flirtatious letters. When the Marine shows up to meet his pen pal, Ellen takes the opportunity to make her ex-husband jealous.