"As the years went by, we drifted apart
When I heard that he was gone
I felt a shadow cross my heart "
To me, this is the key lyric in the song. It's important that the dead friend, isn't really a friend any more. The chorus mentions how the person is "Nobody's hero" - in that their death won't effect the rest of the world. Although, I suspect this is a reflection of the personal guilt felt in the song. The guilt derived from knowing that the person's death won't make a difference to the narrator's life, in any way, since they haven't been a close friends for a while.
"As the years went by, we drifted apart When I heard that he was gone I felt a shadow cross my heart "