I think it is something Harry could only have explained if he truly understood the world that Meghan had inhabited before she met him. Harry had lived a very cloistered life and has no experience of working in those environments, or of the US in general. His life had been solely the RF and the Army. In the Army he was accountable to his direct superiors and ultimately his Grandmother. How on earth was he expected to understand the world of hustling, the sort of background M had come from and her expectations? He was used to ceremony, pomp and circumstance, deference, expectation. She was not. He came from a very large, close knit family living in a strange bubble. None of his relatives truly work for a living, even his cousins. His mother was an aristocrat and his father the future King.
She is a mixed race woman from a broken home. She has no full siblings, and no relationships with her wider family. Even her mother was living elsewhere for much of her childhood. Harry never even met her father. Her lifestyle was completely different to his, her working life utterly alien to him. What he saw of it when he visited her would have been snapshots. He wouldn't have seen her at work, or with her friends in general as their relationship was largely conducted in private until they became engaged. Actually, how could they really have known each other at all? Flying between countries for a few weeks or days at a time, hiding out in their respective houses is not a basis to really get to know someone.
They each had a lot to gain from their relationship . She had a unique opportunity to raise her profile, live in luxury and not have to hustle for work again. He was desperate for a wife and family. She seemed worldly wise, used to the media and with experience of being in the public eye. Most importantly, she wasn't put off by having to marry into the RF as his previous girlfriends were. He was desperate not to lose her, she was desperate not to lose the opportunity. So they clung together, against the world. When she demanded something, he made sure she got it, in case she decided he wasn't worth the effort.
If he had sat down and try to explain how her life would utterly change, she would be expected to do hundreds of things he took for granted, her whole way of seeing the world had to bend to expectations, it would have been impossible for him. He would have had to have seen it through her eyes, and he lacked the capability to do that. She was very stupid not to have taken her time and really got to know the family and the role. They both rushed in because they feared losing the other. Simple as that.