I really like what Chuang Tzu says here... it resonates with my recent (last two years) experience with forgiveness.In the end, with any interaction we feel slighted by, or injured by, it's up to us to let it go. No one else can make it right.
I've come to a 180 degree shift in my experience of forgiveness. I find it has near to nothing to do with the person/behavior/issue any longer. It's about letting go of the story in my mind that I replay about the event and then feast on the injustice/resentment emotionally. Even in the face of an apology, there were times I would not forgive, could not, or just plain didn't want to...
I was not ready to let go yet. My resentment was about me holding onto the emotions of that event.
Forgiveness was about letting go of my attachment to the process of replaying that memory/story.
When I let go and forgive, if it's a person's behavior I'm forgiving, there is no need for me to come to some justification, understanding, liking or approval in my mind over the issue. They are who they are and they did what they did. Much like the conditions of nature.
The act is entirely internal and stems from a desire to stop re-experiencing the story and feeding that energy system.