Oh, come on. Diana was what, 20 when she and Charles married? Can you truly say that you were at your decision-making peak at 20?
A lot of people get married at 20, or at least they used to until recent times. Then they discover problems. Then they work them out.
The problems in that marriage were on both sides. It wouldn’t matter, except that they were the Prince and Princess of Wales, and were supposed to be an example to their country. The problem was, basically, that neither of them was remotely suited to the job.
And I stick by my observation that Diana was a better cover girl than future queen. She was on more covers than anyone in the past 50 years, except maybe Obama.