Being hurt doesn't give one the license to hurt the person back in as much as he/she wanted to. After all, we cannot call it genuine love. When we realized that we're cheated by our partner, the reaction would probably be, we'd wish he/she would feel the same amount of pain.
But when there's already forgiveness for each other's failures and lapses, and these two people still decided to keep the relationship, move on, mend what's been broken and make the relationship even a stronger one that can withstand the test of time, then they should hold on to fight against the circumstances.
Authentic love means authentic forgiveness, and forgiveness means forgetting the past hurts and start anew. But that's not what I see in one situation around me. Just because the girl hurt him once in the past, he would unearth past mistakes anytime he wanted to and get mad and feed in as much as spoonful of hurting, harsh, demeaning words to the girl until he gets satisfied and clear his ego. Make the girl appear as always the bad one. Which he actually thought that being hurt once before, now give him the license to hurt his partner at any given moment.
A part of authenticity in love and forgiveness is accepting the person, regardless of the mistakes he/she made in the past. It does not make any self-gratification because the "I" has always been faithful and good while the "you" was once unfaithful and bad. In other words, if there is truthfulness in one's love, there too must be truthfulness in one's words. Unless when these two people realize that they can no longer find way to mend their broken relationship and call it "quit". But then the case is, the guy wouldn't let go of the girl. He wants to hold on to the relationship and yet he's not making it an even stronger one.
How can there still be love existing in a relationship when one would keep on reminding his partner of the past? How can there be moving on and starting of a new one if one hasn't let go of the past hurts? "The thing here must probably be, until when can there still be respect for each other even when the " I " no longer have the "You". When you just have to keep your silence and then go. It's not easy though, but true love knows what's letting go."