After they spend a night together falling in love, a couple part ways because of WWII, and years later, the man, presumed dead, turns up at her hometown to win her back – only to discover she is married.

Seems similar to "Cast Away"? where the guy's girlfriend? marries someone else after he is presumed to not have survived the plane crash.

Also, it seems delusional and inordinately selfish of the guy to think that she would not marry,? not move on with her life, that she would have a candle burning in the window for him and him alone for 16 years.

When it comes to Romance stories, this is one of my favorite plots.

Unfortunately, that is the main problem with your logline. Since this is a well know plot, you have to tell us what sets your story apart from all other stories based upon the same idea. The more specific the details, the better.