"Save yourself because your dying slowly
say goodnight before you ever say goodbye"
he's telling the person to save yourself, and not to give up. dont die before you have a chance to survive. hence "say goodnight before you ever say goodbye". he doesnt want the person to say "goodbye" and leave forever. he wants him to get away.
and the chorus (i guess you could call it that)
"Save yourself because your dying slowly say goodnight before you ever say goodbye"
he's telling the person to save yourself, and not to give up. dont die before you have a chance to survive. hence "say goodnight before you ever say goodbye". he doesnt want the person to say "goodbye" and leave forever. he wants him to get away.