It does more for the forgiver than for the forgiven. But, to my mind, it should not be a universal, indiscriminate behaviour. I think it is legitimate not to forgive sometimes. It depends, of course, on the severity or duration of what was done to you. Life is too chaotic to succumb to rigid principles.
Conflicts are an important and integral part of life.
One should never seek them out willingly - but when confronted with a conflict, one should not avoid it. It is through conflicts and adversity inasmuch as through care and love that we grow. Human relationships are dynamic. We must assess our friendships, partnerships, even marriages periodically. The past is insufficient in itself to sustain a healthy, nourishing, supportive, caring and compassionate relationship.