This obsession is unhealthy.
You dream of him. Night after night, you dream of nothing but him. The blonde haired blue eyed boy who's caught your attention. Become your obsession. You dream memories from a life that isn't your own, but his. His short life that you, in a sense, ended.
You hope he's still alive somewhere deep inside of you.
Through your dreams, you learn more about him than you even know about yourself. You know him in a way you shouldn't be able to know someone you never really met. You know things about him that he never told anyone else. You know that he snuck up to the station tower and that he thought he was stupid and that he was gay and you know, for a fact, that he wasn't a virgin like he told his friends (who he secretly wished were cooler).
You have the dream/memory of Roxas' first time, and you know that it was your name that he moaned.
It kills you that you can't be with him, but you can't be with him. Because he disappeared to make you whole. Because he is you.
As you fantasize about being able to make him scream your name, you briefly wonder if this obsession could be called narcissism.