One of the hardest truths to admit is something negative about yourself. But, if you can admit it, and apologize you can work towards healing. Then, if the injured one accepts apology you have a reestablished bond.
I'm speaking as a mum who has 34 years of 1 successful marriage.I fully believe that Diana raised William and Harry to always have each other's backs. William will one day be King. He will need his brother to talk to. Harry needs to be the one that William can always count on, through thick and thin.
When Princess Diana passed,Charles was quoted as saying" They are going to blame me". One way towards healing is acting forgiving for what happened inthe past. Being a positive role model for healing the brothers bond is showing a positive emotion towards Diana. Being present when they did something together to remember their mothers legacy (Diana statue) is one way. Another way is to be actively in their lives by communication. Keeping the lines of communication open by text, phone calls, zoom meetings etc. Not to mention, visiting in person!
People are human, and we all make mistakes. But at the end of the day, nothing is as important as family. Harry and Meghan have some apologizing to do. And William and Charles need to be accepting. It will not be easy, because admitting mistakes never is. To have a family in tact is the real key to happiness.