In the Shadows of the Birch Trees - Jeremy Bending

The story of a young Hungarian woman Eszter and her baby Eva who, by an extraordinary twist of fate, escape the horror of the mass murders being committed within the Birkenau extermination camp in WW2 as they are about to enter there.  And of the lives they live following this reprieve.  The SS guard who allowed them to escape, Peter Leahy, falls in love with Eszter and goes to find her in war-torn Budapest.  They are separated again by the return of Eszter’s husband, but never lose their love for one another, living the rest of their lives unaware of the other’s continued feelings.

After fleeing the Soviet invasion of Hungary in 1956, Eva grows into a famous medical researcher into eye disease and eventually uncovers the sad truth that her mother Eszter and Peter both lived out their lives regretting their lost love of each other, before she too dies at the age of seventy after becoming blind.