Person A cheats on Person B.
B forgives A. Then several years later, B falls into temptation and cheats for different reason. A forgives more easier and quicker.
The lady cheated first when she was 19 way back in 2002. He was her boyfriend at the time. They worked it out and we've been long married. He cheats this year and she's more forgiving than he was at the time. This is one of her replies:
My cheating was completely my fault. Nothing my boyfriend ever did nor even our argument was an excuse for what I did.
I always wished I could build a time machine and fix everything. How do you think I've been willing to work with a marriage counseling after my husband confessed his cheating? I owe him one after all. I know what it feels like to be him cheating and being contrite about it. When he took him back at the time, I did made a promise to myself that if he ever cheated, I would work it out too.