Complex sentence: This picture is not so much about the war itself, but about the relationship between the DP of Nikolai and Natasha-the woman that he was searching for all his life, and found a few weeks before his next assignment in the war.
Split into simpler sentences: This picture is not so much about the war itself, but about relationship between DP Nikolai and Natasha. She was "the woman" he was searching all his life, and found her only a few weeks before his next assignment in the war.