Yes, as a pp ;has said - her grandmother, Lady Fermoy, and the Queen Mother were best mates and they definitely (more than) encouraged the match. It was approaching an arranged marriage really.
The problem was that Charles had reached the ripe old age of 33 (imagine!). Times were different then (I mean, on here you get people calling Harry and Meghan at young couple in their early/mid 40s) but in those days it was consdiered that he should have found a wife by that time. The sticking point that while Charles really did have gorgeous, pouting beauties after him (honestly!) in those days, a future queen HAD to be a virgin. Diana at 19 had no ''past', yet she had to undergo a gynae examination to confirm her virginity.
I think I've read that Diana did have a crush on Prince Charles in her teens, so she clearly did fancy him at some point. Whether that feeling was ever seriously reciprocated by him, who knows?
The whole thing was a disaster for both these young/youngish people, trapped in the archaic conventions prevalent at the time. I feel sorry for both of them.