Diana must have been massively damaged and was a selective mute apparently for several years, she was certainly very odd at school but I think things improved when she was a teen. Her mother was against her marrying PC, she was worried that she might not produce a male heir etc . Her father was determined to get one of his girls married to PC I think she was desperate for his approval and attention, once he had custody he was rarely around and sent them off to boarding school
I have read a bit about Diana’s awful childhood before, and find it rather frustrating when posters here and elsewhere write as if Diana was a well-adjusted and perfectly mentally healthy 20 year old when she got married to Charles, and that all her later mental health issues can be laid at his doors. It quite obviously wasn’t the case. She very likely imagined herself in love with the Prince of Wales, but it’s also quite likely she had deep-seated reasons of her own for wanting the marriage, not least impressing her father and/or escaping an unhappy family and becoming fully independent/independently wealthy. They were obviously not well suited, and both were the product of unhappy childhoods. Add in the massive public interest and no wonder it all turned out badly…