It’s an emotion of sorts in that you can’t choose it. You can’t decide to forgive someone, you can perhaps decide to stop punishing them.
I am quick to forgive others and myself. To the extent that it can sometimes irritate me that I haven’t caused any change in circumstances when someone behaved badly.
Which means that forgiveness might have something to do with needing to be acknowledged as having been treated badly and then told that there has been a learning – and move on.
I think those who cannot forgive have issues. And if they can’t forgive you it has to become their problem and you can’t own that.
At some point you have to forgive them for not being able to forgive you.
It could get complicated.