How is forgiveness related to love?
Forgiveness is being good to those who are not good to you. Love, particularly the most difficult form of love, what the Greeks call agape, is to be good to those who are in need of your services, even when it is difficult to offer this love. Forgiveness is one expression of agape. Forgiveness is a specific form of agape in that forgiving takes place specifically in the context of another person being unjust, even cruel, to the forgiver.
There are other examples of agape that do not include forgiveness. For example, a mother who is up all night with a sick child is showing agape because this is difficult and necessary and she does so out of goodness for her child. Forgiveness can occur exclusively in the human heart as the forgiver sees the hurtful other as possessing inherent worth and commits to the betterment of the other. In agape, there is the action within the human heart and mind, but in addition, there is the action of deliberately assisting people in need.