John Green said this quote

... that I forgave him, and that she forgave us, and that we have to forgive to survive in the labyrinth. There were so many of us who would have to live with things done and things left undone that day. Things that did not go right, things that seemed okay at the time because we could not see the future. If only we could see the endless string of consequences that result from our smallest actions. But we can't know better until knowing better is useless.