I've seen similar levels of desperation and bitterness from ex-employees when relationships broke down. (I was the manager of the man in question who had a beef with a senior member of staff)
There's a point where one side feels so bitter that they feel entitled to restitution. More than that. Complete and utter, on your knees abasement to the wrongs that they perceive to have done them. And as a series of people failed to mediate to a reasonable solution, each of those people were added to the line up of "baddies" this man perceived, and added to the list of people who owed him. Now only that, his personal behaviour grew more demanding.
"Let me book this expensive hotel. Let's book this fancy restaurant for dinner. We should get this big drinks tab on work."
The more he hated work, the more he felt it owed him, the less effort he put in and the more he made everyone around him unhappy.
And the new CEO summed it up as, "When nothing you do can make them happy, everyone stops trying."
I think Harry fell very much in love. He put Meghan on a pedestal that wasn't helpful for her, and didn't take advice or support her (I imagine it would have been very different if they'd had an "Anglesey", with Megan acting). Then when things went wrong for her, he reacted unwisely too.
None of this was her fault. He seems a very damaged man without the wisdom or maturity to make good choices for his life.