Volk

Piers Anthony is the acclaimed author of more than 100 novels and short story collections. His books include the Xanth series, the Mode series, Chthon, and Total Recall. 
Volk is Piers Anthony's serious novel of World War II and forbidden love, featuring a romance between a Nazi SS officer and his American friend's fiancée, a pacifist Quaker lady. Politically incorrect, it covers some hard truths. Not all Nazis were evil, and the allies also kept death camps. The author was in Europe as a child, deported in 1940, and raised as a Quaker, so has some basis to address the subjects.