I can see her being like Lily van der Woodsen from Gossip Girl. On her 4th marriage, still top of society and no idea how to parent, but still a little self righteous.I think if Diana hadn’t died Charles and her would have most likely had an amicable if not better relationship. I can see Diana would have remarried and lived abroad. Would be interesting to see what she would have gotten up to. I can see her as one of those philanthropist if society ladies from New York.
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I think Harry would have married earlier and gone for someone with a tighter family relationship. Instead of having mummy issues he’d have had divorce kid issues and would have sought comfort for that. Even if Diana had lived and he split his time between that two parents I can’t imagine a universe where Harry is mentally sound and stable.I think it's a bit hard to say William wouldn't have married as he did, given they met at uni and dated for years. It's a very similar trajectory to other couples with or without parental loss.
Harry there may be an argument, as he seems to have projected a lot of deification of his mother onto his wife. Perhaps he would have married someone earlier if he were carting around a different set of emotional baggage.