The Japanese Lover - Isabel Allende [Historical romance]

In 1939, as Poland falls under the shadow of the Nazis, young Alma Belasco's parents send her away to live in safety with an aunt and uncle in their opulent mansion in San Francisco.

There, as the rest of the world goes to war, she encounters Ichimei Fukuda, the gentle son of the family's Japanese gardener. A tender love affair begins to blossom. Following the Japanese attack on Pearl Harbor, the two are pulled apart as Ichimei and his family are declared enemies and forcibly relocated to internment camps run by the U.S government.