Mariana must be set in the 20s and 30s, only the end is at the start of WWII.
I really recommend Laura Wilson's books
The Lover
Stratton's War
An Empty Death
The first is a standalone, the others are #1 and #2 in a series that now contains 4 books.
The Balkan Trilogy and the Levant Trilogy are set in Eastern Europe in the early years of WWII and then in Egypt.
The Other Way Round is the second part of Judith Kerr's trilogy about Anna (following on from When Hitler Stole Pink Rabbit) and is an autobiography presented as a novel, about a German Jewish refugee family in London during the years of WWII. Although the trilogy are published as children's books, only the first really is (and is stil very worth reading for adults).