The Royals definitely do prenups...the law on prenups changed (ie to make them binding) just before William and Kate got engaged. Coincidence? Or did the RF learn from all the previous divorces....? Without a pre-nup, Meagain would be entitled to 50% of his assets, so you can bet that there is a pre-nup. However, his assets are chump change really (most of the RF's assets are Crown property which means they are really owned by the nation and just 'borrowed' by the Monarch. She is entitled to loan them out eg the estates, the property, the jewellery - but when the papers say she's 'given' that doesn't mean here's a gift, it's yours outright, it just means she has given permission for them to use it on a long term basis eg Frogmore - it's Crown property which is why the taxpayer paid for it to be refurbished and not the Queen out of her private income).
50% of Harry's personal assets wouldn't keep Meagain in private jets for a year. I guess that's why the 'half and half' situation that she's come up with works so well (she thinks) - she gets to borrow all the Crown property and strut around calling herself a princess (FFS) even as the revolting pair are flogging hoodies and doing Primark hauls (#activist) to top up their own bank accounts. And then when the marriage fails, she stays in the US where she has already established herself as People's Queen, superstar actress and all-round amaaaaaaaazing human being, whilst he comes back home to the UK.
If she divorces him, she gets very little, so she's got to keep him sweet - and isolated from his family so he's too proud to admit he made a big mistake.