Caught a doco on William and Harry called the Rise and Fall of William and Harry. I think its a series but I don't know who produced it, happened to be on the Sky Channel at the time, and only saw the last part of it. Had some talking heads/royal commentators who opined about the brothers lives. I don't think they actually personally KNEW the brothers.
Basically the brothers were close until Meghan came into the picture and Harry got married.
When she had a fight or disagreement with Catherine, and it ended in tears, over all things, stockings for the flowergirls/bridesmaids that was when something was not quite right.
So the story goes that William was concerned that things were moving too fast for Harry, as Meghan didn't want to wait 8 years to get married like Kate (now Catherine) did. Harry didn't want to wait either, he was ready to be a husband and father after his previous gfs didn't work out - they didn't want the publicity.
After that the brothers seemed frosty with each other since Harry didn't listen or pay any head to his big bro's 'advice'. As we know in memoir Spare they came to blows after this and Meghan wasn't accepted into the family as readily. Kate had her problems too but not on the scale of Meghan since she was a divorcee, American, and for some, unacceptably 'different'
Harry and Meghans new life overshadowed that of William and Kates now and he was even more popular. The brothers couldn't be together as a trio anymore with Kate like they used to (Kate being a sister-in-law, like the sister Harry never had) .
I really don't know the solution to this since Meghan can't change the way she is and shouldn't really have to. Also I don't think Harry should have married his cousin like the Royal family used to do to keep it all in the family, and now that Beatrice and Eugenie have married, he won't get the chance... But they had the red hair, and grew up Royal, so in paper, they would have made a good match. Never mind about the risk of birth defects. I'm not joking that the Royals used to do this.
Anyone 'outside' was treated horribly or went through a baptism of fire. But this is what families are like, esp those with a lot of money and privelige. Crazy Rich Asians anyone?