I think that there is satire in this song.  I read on some blog that it was written when a relationship ended and it is also called “Good Riddance” -*TIME OF YOUR LIFE*.  One of the people in the relationship was going off on a new adventure in another country, while the other person’s heart was breaking.   The words ‘good riddance’ suggest that the one left behind was happy to lose their significant other or meaningful relationship, when actually they were devastated.   The ‘time of your life’ reference was, I think, a way of honoring all the memories that these people had shared.  It is always sad to say good bye to someone or some time in your life that was special and meaningful, and yet the words, ‘time of your life’ suggest some moment that is exciting and filled with fun.  Everyone who listens to this song will find some significance in it that plays against the actual words.  This music was played at the end of the last Seinfeld Show, and that was a great comedy which people still think about and miss.  I think that is the reaction that you are supposed to feel when you hear this song.