The writer obviously has no idea what the Germans did to the Poles in WW2. A Polish resistance woman falling in love on the spur of the moment and having sex with a German soldier is not going to happen. She would more likely have cut his throat. Plus making love in the middle of a cornfield, Pure Hollywood, and if there were any ripening corn fields the Germans would have confiscated them. Then there is the sergeant, the NCOS were the core of the German army, the idea of a drunken sadistic bully, who lounges about half dressed is also quite improbable.
Then the couple are reunited after the war somewhat like World on Fire