Wasn't it one of her sisters who basically said "You just have to suck it up, Duch" or similar when she was having doubts during the engagement that she and Charles didn't know each other that well?
Mind you, you could say the sisters, who knew Charles well, saw no reason it wouldn't be fine. And since she was troubled even before the marriage they may have just seen it as another of Diana's moods.
I don't know where I read this story, but I read recently of a very awkward scene between C & D. It was a Royal Performance or Gala or something and the whole lot of them were going. Except you can't arrive before the Queen. There was a strict car schedule so everyone arrives in order. And Diana was ready for ages and wanted to just GO. And Charles said "You know we can't arrive before the Queen, I'm having a drink, do you fancy one?" But D just got more and more wound up, going ou to the stairs and making to go, and kept saying "we could just go now" and then when that didn't work "we'll go separately, nobody would notice" (absurd) and was standing at the top of the stairs getting increasingly frustrated and wound up and more pissed off whilst Charles became vaguer and milder and just kept wandering back to the drawing room. The footman (or chauffeur I can't remember) in attendance was mortified. She was raging for a big row, but he just wanted to minimise it and hope if he didn't react it would go away.
It must be stifling to be so controlled, that you have to hang around for ages in your glad rags waiting for the nod to go. And so boring and frustrating, when you're very young. I imagine that is all still the exact same.