Forgiving isn't a mistake all the time

If we never give anybody a second chance, the whole idea of forgiving becomes obsolete. Just why do we find it so difficult to forgive people? We aren't able to do everything right. We aren't perfect. Yet we expect others to be.
Today the other person is on the receiving end. Tomorrow we may make a mistake and ask for forgiveness. And we all know that. Then why can't we just tell the other person that he hurt, but you're taking it for the love of him/her.
Sometimes its just not so bad an idea to forgive, seriously, sometimes people do improve. And if its too hard for you to believe that people improve, you need more hope in your life.