I wouldn't forgive and I would hold a grudge for all eternity if someone just didn't say hi to me or greeted me properly or patronized me
Let alone cheat on me.
I don't forgive anyone. I am always looking for a reason to hold a grudge. Once something has been done it's already out there in the universe. It cannot be taken back. Same thing if something hurtful is said or spoken. The words are also out there in the universe to echo for all eternity and cannot be taken back.