The Dark Arena

The book follows Walter Mosca, an American Second World War veteran who is forced to return to Germany for his girlfriend, Hella.In this story, GI Walter Mosca gets involved in a local shackup arrangement in Germany at the end of WW II, comes home to find that he can no longer relate to the Girl He Left Behind, so he returns to Germany as a civilian employee to seek out the girl he hadn't realized he was falling for. Her effect on him causes him to be a lot more analytical of his own behavior towards the locals in general, that of his colleagues as well--but more than that, it also gives him a view of the perspective of the people he's there to help "keep in line". All sorts of things can happen to a person's worldview when he becomes romantically involved outside his native culture. I have no actual details on which to base this, but I wouldn't be a bit surprised if the late Mario Puzo drew on his own experiences in service during WW II as source material.