I'm reading The House keeper's Diary, discussed several threads ago.
Interesting. Diana and Charles were a terrible match. They had nothing in common. What they most had in common was a shared devotion to their sons. (she also mentions they both had a strong sense of public duty). At first they both tried to make the marriage work (her more than him) but it was never going to.
It's an insight into the privileged world the royals live in. And how it's quite unhealthy and breeds selfishness and arrogance.
Sarah Ferguson, before she married Andrew, was described as a pleasant, down-to-earth, slightly ditzy but very likeable upper-class girl, a genuine breath of fresh air.
After her marriage she became selfish, entitled, unreasonable and rude to staff.