I only watched clips of the engagement interview and enjoyed the wedding. The moment I started to think a life of Royal service wasn't going to work for them was when Meghan said that nobody had asked if she was ok, whilst on tour in South Africa. It was the opposite of what being royal is about, drawing attention to yourself rather than the people you are meeting. The fact that Harry was also making it about him, in the middle of a tour, made it pretty clear that he was not the Harry palace PR had created.
I thought that it was probably best they left and lived a lovely private life but the grandiose "internationally protected persons" statement, released without notifying the palace, made it clear that wasnt going to happen. From then it's been watching them make bad decision after bad decision, ruin their popularity all made worse by terrible, unlucky timing.
I still maintain though that Harry should bear the larger part of the blame because he knew the life he was asking Megan to join and he clearly never once chose royal duty and public expectations of the monarchy over his own arrogance, bitterness and entitlement. When he chose to leave he could have left with dignity and goodwill but instead flounced out trying to burn everything down behind him.
Which he didn't achieve and which he won't. The monarchy has survived far worse than the airing of a Spare's grievances. What will ultimately end it, imo, will not be a scandal but simply society deciding that the institution no longer fits with how society sees itself. Time and cultural change will end the monarchy, not lies and tantrums or even scandal.