There are so many conditionals required to make this statement valid that it’s pretty much useless.
A list of conditionals would be boring, though. Let’s zoom out and talk about what forgiveness is.
Most of the time, we use the word ‘forgiveness’ either to mean a transitive act (I forgive you) or a state of reconciliation.
As a transitive act, forgiveness originates in the mind of the one who has felt violated by another. This act can be sought by the violator (‘Can you forgive me?’) but any state of reconciliation can only be realized by the violated person.
What is this state of reconciliation that we also call forgiveness? That’s up to those involved but its essential attributes are (1) a unilateral adjustment in the mind of the violated person, not the violator, and (2) direct communication of this intrapersonal change from the violated to the violator.
If both of these criteria are met, the transitive act of forgiveness is complete.
I realize that might sound like a truncated description of forgiveness. What can forgiveness mean if the person who is being told that they’re forgiven decides to reject that message?
As I see it, there are two mutually exclusive reasons for why someone might reject another’s forgiveness. One possibility—the one that you alluded to—is that the person believes they did nothing wrong and therefore doesn’t feel any reason to believe they need to be forgiven. But the other possibility is that this person may feel unable to forgive themselves.
This last point highlights why the second criterion for the transitive act of forgiveness is about communication and not changing another person’s mind. Because that second transformation is not certain. When the violated person says to the violator ‘I forgive you’, they are not just communicating their own intrapersonal transformation, but also their blessing for the violator to make that transformation themselves.