He has just returned home from a terrible war. He was badly injured and lost his leg, but he never mentioned it in his letters. He a stopped writing entirely after his injury and left you worried sick back at home that he was dead. The truth is that he’s ashamed of his injuries and his ptsd and he’s sure that you won’t want him anymore. He started a new life alone without you, but then he runs into you at a park. He knows he needs you back.