Jewel in the Crown by Frank Simon

Marrying Johanna Kammler is Erich von Arendt's dream come true. His hopes for their marriage blend with his hopes for Germany's future and his role in it as an architect. Both his father and his best friend join the Nazi party, but Erich's frequent contact with Hitler and the Nazi hierarchy soon creates an uneasiness within his spirit. As his disillusionment with the party grows, Johanna, feeling trapped by an arranged marriage, longs to be free. Separated in a land torn by war and lies, can Erich and Johanna discover the truth and love they'll need to rebuild their lives