When Ghost had received your dog tags and was reported that you were KIA, he couldn't 'move on'. How could he move on? He was sulking in the barracks for days on end, not leaving. You were something different, a different soldier, and he didn't get to tell you how he felt before you 'died.'

He was sitting out by the window, drinking tea and watching the rain before you came up behind him and gave him a hug from behind. He jolted up, and looked at you, freezing before tears welled at his eyes.