as he approached middle age he might still have become a disgruntled, unhappy man
I'm not sure if he would have. When he was surrounded by happy, positive people, like Chelsy, William, Catherine and his military friends, he was known for being a party animal, very sociable and full of fun. It was only when he met up with the Megan; who herself already had a track record of broken relationships, failed friendships and discord with family members, that he began to change. If you compare photos of him pre megan/post megan; the difference is astonishing. Their relationship rather reminds me of the Archers storyline with Helen and Rob Titchener; love bomb and then start to slowly separate them from their friends and family. For a middle aged woman, she has remarkably few family members, ex colleagues or old friends who have remained in contact. Bit like Rob Titchener.