I know it's rare but it does sometimes happen that after a break up/bad treatment by one person, a couple get back together and it works out.
Eg. couple I know married 10 years, 2 kids, happy family first got together at university. He was awful to her at university - basically slept with her a couple of times and mucked her around. Behaved like an utter sh*t. They had a friendship group in common and stayed in touch. Rest is history. Happy ending.
I was wondering when is there a way back from bad treatment and a happy future? What does it depend on - forgiveness or the other person changing? What things should you be looking for if you want to give someone another chance?
Is it only when people are young and then a lot of time goes by and they mature? Or is it possible that as an adult after a lapse of time, you can move on and have a happy future?
I know in most cases the answer will be "forget it; once an ars.ehole, always and ar.sehole"; but looking for guidance as to those rare cases and examples of them.