I think there was a bit of dynastic stuff going on too. I am no history expert but I believe the Spencers thought they had a claim to the throne, and that may possibly be why they were keen for one of their daughters to marry the heir, so Spencer descendants (ie Prince William) would inherit the throne. It's possible Diana grew up vaguely knowing that she might be that person. It went wrong for her older sister. Normally I'd not expect two sisters in the same family to enter into a similarly affectionless relationship with the same man.
Baby Reindeer - anyone watched it?
Alphabetical girls and boys names January 2024