Move the interest of the reader more toward the characters and less into the storyline. Don't set out to write a sappy story...have an objective, create the characters, and then let the situation evolve between them. The reader becomes involved in the characters and does not notice that you put them in a sappy story until they are butt-deep in tears.WB.
It's hard to say without reading the story but for me things seem sappy usually when they become generic and cliche. Like saying you "got lost in someone's eyes". I think the adage of showing rather than saying is helpful.
So for example, I was in love with a girl recently, and one day she left work early to go get plates for her car and when she came back I asked her if she had gotten a plate for her car and she said "it doesn't eat" which I thought was pretty darn funny.
But, whether you like that story or not, it is better than simply saying, I liked this girl and she always made me laugh.
Throw in some ninjas, a fire fight, explosions, an armada of A-10 thunderbolts screaming across the sky, tornadoes, big beefy engines that propel monstrous machines across the landscape, chicken salad sandwiches, ravenous dinosaurs, swordfights, roaring maching guns, fire breathing koalas, volcanoes, belching, a lot of Star Trek technobabble, bedouin warriors, dunebuggies with machine guns, flying motorcycles, laser blasters, Dr. Michio Kaku, fast cars, superheroes, angry ghosts, fiery demons, crunchy snacks, the battle between good and evil, giants that shove trees up their enemies bottoms, spaceships with weapons that go "PEW PEW PEW! ", monsters from the Id, puppies and kittens, radioactive beasts from alternate dimensions, and all washed down with a heavy dose of humour!
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.