During the "Falling Stage," the hero falls under a "dark power." Early in the story, we don't exactly know why war is a "dark power" yet, but we do know that war is generally considered to be a bad thing.
This peaceful afternoon in the tearoom is kind of the calm before the storm. The soldier knows that he's about to depart for military action, and we know that the threat of battle is immanent. However, he's still able to enjoy this reprieve from the war.
Time has elapsed, and a lot has happened in the life of the soldier over the last year. He's seen action at D-Day and beyond, and now that the war in Europe is over, his soul has yet to recover. Sergeant X, as he's now known, is emotionally numb and alienated from his former self.
This is not the soldier we knew from the tearoom – all of a sudden, we see just how much the war has warped him. We worry, as he does, that he'll never find himself again.
During the "Rebirth Stage," the hero is redeemed, usually by a woman or child. Esmé (who is fortuitously both a young woman and a child) helps the soldier reconnect with the world, and with his old self. Finally, there's light at the end of the tunnel – it looks like he just might pull through.