Never Say Goodbye (movie, 1946)

Phil and Ellen Gayley have been divorced for a year, and their 8-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.