When someone is unable to forgive another do you think the main reason is because they've never done anything wrong themselves to the degree that would need forgiveness? Not that this should be the reason to forgive someone.
Are there other reasons and if so are they a lower percentage of the reasons?
Edit.
I think it's not either person's fault. It's accepting we have the right to feel emotions without needing to feel we have "inherited sin." It's in our US culture. Instead, we can do things to relieve our hurt without blaming ourselves because of feeling the way we do. To admit: I am hurt. I did nothing wrong. Let me do this to relieve my feelings because I can't control how others feel, do, and say is probably the best thing one can do if they can't do it literally.
For example, I didn't do anything wrong (I was ignorant of the situation in order to do so) and my father may have done something wrong depending on the perspective you see it from. Grandmother died near four years ago. She was dying of cancer. Father didn't tell me. I barely talk with him. I haven't experienced grief like that and one thing about grief is there is anger and such. It's not the person's fault. It's not the person who grieves fault. It's a process.
Father is developing alzheimers. He's forgetting a lot. So, if I did tell him I forgive him, he wouldn't remember. It would be more for me and I technically want it to be for him. So, in this case I'd have to settle my own feelings because I can't change what he has done (not tell me about her death, among other more hurtful things). It's the past.
So, in some instances we should forgive. It helps our sanity. I just don't think we should fault ourselves just because we choose not to forgive or forgive ourselves. I honestly don't think that's the point. It's an original-sin thinking and we can forgive ourselves and others without seeing either doing anything wrong. Father didn't tell me because he didn't want to hurt me. It's all in perspective.
Sorry. Took awhile to even get this out.