Why does Addy end his relationship with Eliska in the novel, We Were the Lucky Ones?

Addy falls in love with Eliska at first sight, and ultimately asks her to marry him. As their relationship progresses, however, he realizes that he cannot be honest with her. Eliska tells Addy that she would prefer they focus on the positive things in their lives, the things they have to look forward to, and he therefore feels like he cannot be honest with her about his all-consuming concern for his family. Because of this, he decides to end the relationship.