Why would anyone want to display her/his dirty laundry in public?? Merriam-Webster on dirty laundry: “private matters whose public exposure brings distress and embarrassment”. The reasons that I can think of are both positive (ie, Love) and negative (eg, hate, revenge & retaliation).
The British media focus on my negative explanations. My perspective is different: you must love someone immensely in order to reveal your family’s dirty laundry. My explanation has a drawback: why was she unable to convince him to protect him from himself? Harakiri should not be in her/their interest.
Unfortunately, Love is rarely – if ever – equal in a relationship (eg, EliteDaily, Quora). At the end of any relationship, there is always someone who wins, and someone who loses. As a spare to the British throne, he is unlikely to lose. I doubt that she can win, at the end of their relationship.
Early 2016, I published my blog The ledger of a relationship. Its first paragraph states:
We all keep score in a relationship although the reasons may appear to be very different. The pluses and minuses are carefully written down in our memories. Minuses are amplified and compared with past experiences. Although financial warnings claim that “past performance is not indicative of future results”, our emotional alert system does think so. To many people, the past negative experiences do seem indicative for the success in their future relationships.The ledger of a relationship (2016)
I wonder how both will look back at the above: did it strengthen their alliance / bond, or did it cause a rift? I’m inclined to believe that he will once blame her. True love implies that you disregard your self-interest and protect the interests of your partner, even when not convenient.
Last but not least, in my view, he is probably right in his family’s assessment but why does he need, want or believe in being in the right? In my view, only Love can explain the course of his actions.
“Do you know what love is? I’ll tell you: it is whatever you can still betray.”  “Betrayal can only happen if you love.”Quotes from The Looking Glass War, a 1965 novel by John le Carré (1931-2020), “a British and Irish author”
I make my livin’ off the evenin’ news
Just give me somethin’, somethin’ I can use
People love it when you lose
They love dirty laundry
Note: all markings (bold, italic, underlining) by LO unless in quotes or stated otherwise.