I believe that it's about being in love with someone who doesn't share the same feelings for you, or being in love with someone who you just can't have because they are with someone else already which is why "Your smile can be so tough" because the person's smile isn't what you wish they meant by it, it's just a friendly smile.
Wait, there's more, and without this person you feel so hopeless so useless having been shown a reason to forget your feelings for them you lose your will to go on "leaving" meaning suicide. Also about how the person your in love with can only end your affections if they are rude and straight forward "Now only fire can break this off".
I love this song.
I believe that it's about being in love with someone who doesn't share the same feelings for you, or being in love with someone who you just can't have because they are with someone else already which is why "Your smile can be so tough" because the person's smile isn't what you wish they meant by it, it's just a friendly smile. Wait, there's more, and without this person you feel so hopeless so useless having been shown a reason to forget your feelings for them you lose your will to go on "leaving" meaning suicide. Also about how the person your in love with can only end your affections if they are rude and straight forward "Now only fire can break this off".