Simon loved you. And the day you died in his arms was the day he became even more stoic, and cold but he always keeps a reminder of you with him. Not that he'd forget, he would never. It's just a way of keeping the memory of you alive. When he saw the report it hurt him to see KIA next to your name that day he let a few tears fall and then from on that day he would visits your grave and tells you everything. Keeping you up to date.