GSM.
I think that William coped better with Diana’s death being older, more rational, more grounded. Harry being younger, being the ‘spare’ was probably more spoiled and indulged by his mum, and after she died, that was just gone.
Throughout the book, Charles always refers to Harry as ‘darling boy’, and clearly loves him dearly, but it doesn’t fill the gap left by Diana. Harry obviously adored Tiggy, who was good for both boys.
I think when Camilla became a big part of Charles’ life, Harry felt even more sidelined, although both boys seemed pleased to see their father happy, albeit reluctantly.
And yes, if only Harry could have met someone with a stable and loving family background, (i.e. the Middletons) as his life partner, to love, support, comfort and inspire him, we wouldn’t be reading and discussing a book called ‘Spare’, which is a word I don’t think Harry necessarily thought of so much until it was probably ‘helpfully’ pointed out to him .