Charles' so-called "public humiliation" - I think he brought that on himself.
Whatever anyone may say about Diana and her affairs later on, she was a young naive girl aged only 19 who married a much older man of the world who was in love with Camilla. Charles admits himself that he had doubts before the wedding and that he cried the night before.
As the older and more mature of the two of them, he should never have allowed Philip to push him into the marriage, but he needed "a virgin bride" and he had run through most of the selection available.
Camilla had done the dirty on him by marrying Parker Bowles while Charles was away, and also Camilla was back then a Catholic, I believe, and so it was frowned on that Charles should marry her. She was also a woman "with a past" and her history was considered too racy with previous sexual relationships for her to marry the Prince of Wales.
Diana didn't go into the marriage planning to have affairs, and her mental health was affected by a desperately unhappy marriage. Those of us who have been there can understand, I think.
Both of them came from dysfunctional childhoods. Diana never recovered from the abandonment by her mother, even though that was not her mother's choice and was fought through the courts, and I think it is perfectly understandable that she clung to her remaining parent and was jealous as she grew up. There was still that abandoned little girl inside her.
Charles meanwhile had a different but nevertheless dysfunctional childhood, and both of them wanted "Mummy" in a partner. Charles was too selfish and self-absorbed to be understanding and a support to Diana, and has found "Mummy" with Camilla, who looks remarkably like the nanny he had whilst growing up, and panders to his whims. Diana never found that.
No doubt Annie will come back quick as a flash and tell me I am totally wrong about all this
!!