We are bound to experience offenses in life. But as children of God we are meant to forgive. Our hearts should be void of grudges. We do not please God if we hold people in our hearts. Even though the person does not deserve it we still should go on and forgive.
These are part of the things that God expects of us as christians to observe. No one is saying it would easy all the time, but notwithstanding we should be able to let go.
If Christ was forgave us of our sins then we also should be able to forgive. If we have any idea the number of times that we have gone against God in one way or the other we'd be amazed and wonder how come we are still standing. This is because God had pardoned us countless times and He expects that we do same to others. That is why Jesus told Peter that even if he is offended he should forgive the person seventy seven times.