Who is Paula from The Forgotten Soldier and what is their importance?

Paula is a German woman, about nineteen years age, who lives near the parents of Ernst Neubach. Sajer meets Paula while he is in Berlin on leave. At first, she treats him circumspectly because he doesn't speak good German, and he appears to be emotionally confused. At the urging of Ernest's parents, Paula spends some time showing Sajer around Berlin, a place he has never visited before. When Sajer departs for the front, Paula gives him a care package that includes a photograph. They exchange letters for many months, but they never see each other again.