Tomorrow is Forever (1946) fits the bill.
John Andrew MacDonald (Orson Welles), whom the U.S. Army mistakenly declared dead long ago in the European War, returns to the U.S. decades later to discover that he has a son and that his widow Elizabeth (Claudette Colbert) is remarried to a another loving man -Lawrence Hamilton (George Brent).
John now lives in the U. S. as a former citizen of Austria under the name of Kessler. His wounds have disfigured him beyond recognition, so when Kessler shows up as consultant to Hamilton's business, Elizabeth has no clue she's shaking hands with her first husband.
Great conflict is an opportunity to express great love. If we define love as doing what's best for the other person regardless of the benefit to oneself, there's plenty of love to spare with these characters.
- the compassionate man who becomes loving husband and adoptive father to a lonely widow and her son.
- the biological father and son who share an ability to see beyond personal discomfort and express a love of family and country despite the risk of the ultimate sacrifice. In fact John says to his wife on his way to war, "Let me love you in my own way."
- the love the son has for his parents, never wanting to bring sorrow to their lives.
- the love of a mother for her son. Elizabeth doesn't want Drew to die as her first husband did.
- the love and respect John has for his wife's new family. You can see him gauging his options, never wanting to intrude.
Despite the fact that its title sounds like that of a cheesy James Bond film, Tomorrow is Forever is a solid story about love -actual love- on many different levels between and among its characters. It'll keep you guessing and hoping each character makes the right decision. Highly recommended for Valentine's Day (or any other day).
- Watch for a charming performance from Natalie Wood as a war orphan that Kessler adopts.
- For a comic version of a similar story of a spouse believed long-dead who shows up again, watch My Two Husbands with Jean Arthur and My Favorite Wife with Cary Grant.