This advice applies to relationships at any point in life, regardless of whether it's for kids or adults.

1. Assess the importance of the relationship. If the relationship is important, then perhaps there's a legitimate reason to be upset. If, on the other hand, "bad things" happened with a stranger with whom we don't talk to/communicate with anymore, there's no point in fighting about it or stressing over it.

2. Assess the importance of the incident. What did we fight about? If the issue is significant and needs to be straightened out, straighten it out, but if the incident is trivial and will not be significant in the future, just forget it.

Bottom Line: There's a saying concerning minor incidents that happened many years ago. It goes something like "If you didn't fight about it then (i.e. YEARS AGO), what's the point now?" Basically, life is too short to be arguing/fighting over trivial stuff. If something happened years ago and has no bearing on whatsoever on the future, let it go. The future will be brighter that way! Now, some people will remain angry, but that only makes the situation worse. These people should "Forget" the incident, but never "forgive" the person/people who caused them the pain/suffering.