time and healing
Time heals all wounds. However, just like one is sentenced to different lengths of time in prison depending on the crime committed, the time required for a wound to heal depends on the depth of the wound inflicted.
If someone really fucks you up, it takes a longer period of time for you to forgive that person. However, unlike the pact between an individual and society at large, a relationship between two individuals can not be put on hold forever.
The maximum amount of time a relationship can be put on hold depends on its current strength. If that maximum is shorter than the expected length of the healing period, we drop the relationship completely and write that person off.