The lost wife / Alyson Richman.

Enhanced descriptions from Syndetics:

A rapturous novel of star-crossed love in a time of war--from the international bestselling author of The Secret of Clouds .

During the last moments of calm in prewar Prague, Lenka, a young art student, and Josef, who is studying medicine, fall in love. With the promise of a better future, they marry--only to have their dreams shattered by the imminent Nazi invasion. Like so many others, they are torn apart by the currents of war.

Now a successful obstetrician in America, Josef has never forgotten the wife he believes died in the war. But in the Nazi ghetto of Terezín, Lenka survived, relying on her skills as an artist and the memories of a husband she would never see again. Then, decades later and thousands of miles away, an unexpected encounter in New York leads to an inescapable glance of recognition, and the realization that providence has given Lenka and Josef one more chance.

From the glamorous ease of life in Prague before the occupation to the horrors of Nazi Europe, The Lost Wife explores the power of first love, the resilience of the human spirit, and our capacity to remember.