What is the difference between forgiving a person and trusting that person?
Forgiveness is a moral virtue as is (for example) justice, patience, and kindness. A moral virtue starts within a person as goodness and then flows out to others for their good. In the case of forgiveness, an unjustly treated person has mercy on someone who acted badly toward the forgiver. One can offer that mercy without trusting a person if he or she continues to behave badly. Trust must be earned. Forgiveness can be given unconditionally as compassion, mercy, and even love no matter how the other behaves. At the same time, one who forgives does not toss the quest for justice aside. One can forgive and seek justice.