Many times people do forgive but still don't forget it and/or let it go..
Many people become slaves to their own memory. Yet, if one doesn't remember, one can continue to make the same mistake over and over again..
Therefore, to remember and learn and then to forgive and let go, allows one to move on on the karma energy processing process..
Also, IMHO, to say that it never happened is denial and not necessarily forgiveness..