The act of forgiveness is done internally and in silence. If you don't forgive, you will be kept in mental struggle and negative and intrusive thoughts will continue to manifest. Even unconsciously. Anger and resentment builds, therefore.
Discussion
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.
To anger be built, the situation at hand must be, at least from the perspective of the "victim", really bad.
You don't go over a psychopath, or a violent person and ask for forgiveness. Chances are you put your life at risk and they will "play you" all over again.
Yes, two adult persons, healthy ones, can forgive and be forgiven over a conversation. Redemption does not need an agressor to ask for forgiveness, he can simply just change behaviour.
Unfortunately there are some people in this world that damage other people's life, forever. The act of forgiveness is essential to have a better life. That does not mean excuse or forget what has been wrongly done.
The etymology of "excuse" is:
"attempt to clear (someone) from blame"
also:
"pardon"
ex (meaning out or away)
causa (meaning accusation or justification for action)
The etymology of forgive is to "grant or pardon". Something that cannot be done solo.
I disagree that forgiveness (of people that aren't sorry) is essential for a better life. Better than what? Is my life so horrible because I won't forgive my mother in law for removing the dog? I have no emotions regarding the issue.
If pretending that forgiveness took place helps you process your emotions, and get them out, then it's healthy, but it's not forgiveness. If it's just a way to ignore your anger, it will kill you.
It is, when the act of forgiveness does not allow the person to move forward in life in a healthy manner.
You are using an example of a situation that does not implys a degradation of ones life and relations.
Have you ever felt anxiety?
Have you ever felt anxiety, every day, in an extend of 3 years, constantly, non stop, all the time? Do you know the repercussions of it on a daily basis? People tend to isolate, they do not want to be around other people, everything triggers them, they also don't want to be a burden to others.
Everything exists on a spectrum, and not everyone react the same way in different situations.