Our Love Will Be Legend

Three months after Eren's death, Levi killed himself. They all pretended to be surprised--the rest of the world genuinely was, but in the Survey Corps, they all had their own witness of the strong love shared between them. Years later, Commander Armin Arlert decides that he can't let the story disappear forever, so he writes to each of his friends and former comrades, asking them to share their story of him. He's kept the letters for years. Yet, why couldn't he bring himself to write the epic?