Forgiving, again, and again, and again. Forgive me if I carry on with this topic forgiveness, even if I get repetitive.
When I was a kid (about 8), I scraped my knee pretty badly. I wasn't in a context of close adult supervision, so the wound was never cleaned or bandaged. The scab was huge. I couldn't leave it alone. I kept picking at it until it got infected. I would squeeze out the puss, a scab would reform, and I would pick at it some more. It took months for the wound to heal (thank God I didn't get blood poisoning). Well into adulthood, I had a scar on my knee from that wound.
Forgiveness, in my experience, is much like healing a wound. If we have good spiritual care and we follow instructions and the wound is not too severe, we can heal (forgive) pretty quickly. However, if we are left to own devices, if we have bad advice, or don't follow good advice, emotional and spiritual wounds can fester and become gangrenous and eventually kill us. This is especially true if we keep picking at them: if we keep calling to mind past wrongs and experiencing afresh past pains.
One aspect of forgiveness that causes some confusion--and thus adds to the picking--is the association of forgiveness with punishment. In a juridical context, sure, forgiveness means not receiving punishment. However, experiencing consequences is not the same as being punished. God forgives us our sin, yet we still experience many of the consequences of our sins. This is an aspect of human freedom. Freedom wouldn't be real if consequences were not real. If I chose to go left, but experienced the consequences of the path on the right, then I never had a real choice. While forgiveness averts punishment, it doesn't change consequence.
God may forgive me for hitting my brother, but the black eye doesn't suddenly go away. In fact, although my brother too may forgive me, the emotional or mental sickness or instability that originally impelled me to hit my brother still needs to be healed. Moreover, my brother having completely forgiven me, may still want to stay out of arm's reach for a while--at least until he has reason to believe that I have begun to lean how to control my anger. This staying out of arm's reach has nothing to do with forgiveness. Forgiveness was a matter of my brother's heart. Staying out of the way is a matter of wisdom. A man who has shown that he has anger control issues should not be treated as though he really doesn't struggle with such issues. That would be stupidity, what is commonly called codependency. That is not forgiveness.
Sometimes people have a hard time healing emotionally and spiritually because they cannot separate these two matters, forgiveness and consequence. This confusion is like an infection that poisons emotional wounds. In order for the wound to heal, forgiveness is necessary. But forgiveness seems impossible, or at best foolish, when it is tied to (A) second chances (third, forth, fifth, sixth, chances) or (B) to trust.
Forgiveness does NOT mean an automatic second chance. Forgiveness does not equal trust. Forgiveness means that I have stopped picking at the wound in my heart. Forgiveness means that I do not hold your trespass against me, against you. I forgive you, but I also now know you better and will treat you according to that knowledge--not to punish you, forgiveness lets go of punishment. I will treat you according to my knowledge of you so that you can heal, so that you are not soon put in a situation where you will be tempted to commit the same trespass again.
This is good for you and safe for me. Forgiveness does not throw wisdom and common sense out the window. Sins have consequences, and forgiveness does not make those consequences go away.