O

The first part of this song was originally called "Fly On" with the second part being "O" by the band decided to dispense with double song names.

I think the first part is a statement of unconditional love and a goodbye. It is Chris, saying to his ex-partner, "you know what, you're an amazing person and you need to go off and be amazing but I need to change my life. Maybe one day I'll be as amazing as you.".