One of the reasons many of us struggle with friendship is because we have been hurt in the past. We should expect that. Hurt comes with the territory when it comes to relationships with people because every person is a sinner. If we are going to have friendships that last we need to learn to be courageous enough to share with others when they sin against us and hurt us and be merciful enough to extend forgiveness if and when they repent. (Colossians 3:13-14 is a good companion text for this one.)