Lyric discussion by zaroou 

Cover art for The Amen Corner lyrics by Opeth

I don't think this song is about a new man at all, rather that the ghost sees that the bond between him and the girl is breaking ("The bond we never spoke of, once stark and enticing, now slowly smoldering to dust"). Seeing as the name of the song is The Amen Corner, it is likely that religion or praying is the main reason the ghost feels that he is losing touch with the girl. This is highlighted by the fact that she turns to religion to consol herself ("Hiding your face in the palm of your hands"), where it is shown that he dislikes this as he says she is "Finding solace in the words I do despise". He feels that the only way he can regain the bond that was lost when the ghost died is to "[rise] from my sleep" and make his presence physically felt. He sees this as a last resort, as it is "The final spark that blew life into me, the Demon of the Fall". This is why he terrifies the girl in the next song on the album; not to kill or harm her, but as a desperate attempt to regain their bond with one another.