What keeps us from forgiving the people who hurt us is that we have not yet healed the wounds they inflicted. Forgiveness is the gift at the end of the healing process. We find it waiting for us when we reach a point where we stop expecting "them" to pay for what they did or make it up to us in some way. Yet, forgiveness is moving on. It is recognizing that we have better things to do with our life and then doing them.
Ideally, friendships lead us into deeper communion with each other; those we love mirror the divine reality and so draw us closer to the One they reflect. In our humanness, however, we can forget that the friend is only a reflection of God and instead invest ultimate meaning in the relationship.