I'm trying to find out what movie I have seen a few years ago.
The action takes place in occupied France if I remember correctly. The first part is more like love story between a man and a woman. After this man enlists in the army and leaves to fight, the woman apparently has an affair with a local nazi commander or something. When the man comes home finds out about the two and tries to convince her to leave him. Unfortunately she can't tell him the real reason why is she involved with the nazi guy, but later the man finds out that she actually enlisted as a spy for the French resistance :D
In the end, the french resistance manages to overtake the nazi occupation, but the woman gets caught by french people and she is considered a traitor because everyone who lived there saw her with the nazi commander.
The man tries to find her, but she eventually gets killed by the angry mob :(
It has one of the most frustrating movie endings I have ever seen.