Psychotherapy helps people in two ways. First, it helps people understand how their minds work which usually helps free them from repeating irrational and destructive patterns. Second, the therapist seeks to help patient have corrective emotional experiences that counteract their self-destructive and defensive beliefs. The combination of insight and new corrective experience, both inside and outside the therapy relationship are what provide the engine of therapeutic change.
Heartfelt apologies are rarely given but, when given, are usually profoundly healing. People resist apologizing because it opens the door to feelings of terrible guilt. Having committed a hurtful offense becomes (falsely) equated in our minds with being a bad and horrible person. The person receiving a sincere apology, on the other hand, feels absolved of guilt and shame, feelings which were excessive to begin with.
Popular culture celebrates the importance of forgiveness, particularly of children forgiving their parents. Unfortunately, too often such forgiveness is simply a repetition of a universal, albeit self-destructive tendency in children to let their parents off the hook in the service of maintaining a connection with caretakers upon whom children are completely dependent. Facing the pain that parents were responsible for inflicting is usually a necessary part of psychological growth and, ultimately, of self-forgiveness.