We all have our own unique view of life and to judge someone saying "thats wrong" is like saying "your view of life is wrong" because it doesnt match our own values/believes etc.
I understand what you're saying here Colin and I do agree to a point. The stories we tell ourselves are amazingly powerful. I think this is very true in lots of circumstances but the times when people are most likely to hold grudges are the times when they feel harmed by another's behaviour. When a person actively puts another person at risk (physically, emotionally, whatever), then community standards would say "thats wrong". It's all kind of on the same continuum for me. Minor insults from another person or being snubbed etc are usually seen as being 'wrong'. I can see the value in changing my perception of that person to let go of the hurt. If I change my expectations of them (i.e. that they'll be polite) then I won't feel any grudge towards them. But what about if they rob me a knife point? Kidnap my child? Murder a family member? I'm going to have a grudge and it's going to be very hard to convince me that it's just my values or beliefs that create the grudge/ill feeling. I think there are some general, basic standards of behaviour that we all expect from others. And that will lead to grudges if those standards are not met. And I know victims of crime can forgive their perpetrators, but that is a process that can take a long time and a lot of hard work. The grudge is there initially.