You don't have to be angry at someone to not forgive them. I'm don't agree that my mother-in-law should have sent her adult daughter's emotional support dog out of the house, but I'm not upset by it. I don't see any purpose or benefit to attempt to convince myself her actions are acceptable.
Also, I completely disagree that forgiveness is solo activity. You can't forgive someone that doesn't ask for it first. The rest is ego-stroking.