Releasing the pain someone has caused you or you have caused yourself. I read that there are three levels of forgiveness :
Exoneration - you can see that it was a mistake and the person acknowledges their wrong. Your relationship is meaningful you are open to it being restored
Forbearance - there is partial acknowledgement ,perhaps an insinuation that you were partially to blame , causing them to behave poorly. You maintain ties but it is a watch and evaluate situation that may work into exoneration.
Release- you forgive the incident , release the pain and bad feelings ,but because there is no acknowledgement on the offenders part the relationship is terminated and you move on.