Sometimes you have to accept there’s only so much you can do for a sibling.
For 20 years, after those tragic events in 1997, you were a rock for your brother – the only other human being he could entirely open up to and trust.
Your father was often absent and distant. Given the deep-rooted bitterness you and Harry both feel about the way Charles treated your mother, the paternal relationship was understandably strained for many years.
As a result, you often took on the combined role of Harry’s surrogate dad, chief-of-staff and best friend.
It wasn’t always easy. Especially as scandal followed scandal for your brother – the drugs, the Nazi uniform, the drunken altercations, the racist language in the army and the strip poker incident in Las Vegas.
But you always kept the faith, with calm and wise counsel behind-the-scenes, imploring harsher members of your family to give Harry the chance to grow up while making mistakes.
Prince William, Prince Harry and Prince Charles after Princess Diana’s funeral at Westminster Abbey in September 1997
The Duke of Cambridge (left) and his brother Prince Harry at the opening of the Greenhouse Centre in London in April 2018
It was you who convinced Harry to seek professional help to deal with his mental health problems sparked by the death of Diana. He first saw a counsellor after you reassured him by saying: ‘Look, you really need to deal with this. It is not normal to think that nothing has affected you.’
When your wife Kate entered the scene, she immediately bonded with your brother too, becoming a trusted companion and then a work colleague.
Your bold and brave charity initiatives as a trio revitalised a tired and fading monarchy, providing some much-needed hope that young people would keep the faith with the Crown.
In that context, it is completely understandable that when a fame and power-hungry American actress entered the scene and stole your brother’s heart, you asked some difficult questions about the courtship.
No one with any sense blames you for gently querying whether Harry should take some time before he married someone so apparently prepared to give up her career and life in the US to enter the British Royal Family.
Many of your early fears have tragically come to fruition.
Your guidance encouraging Harry to take it slow and not rush into any hasty decisions was rooted in love and concern, certainly nothing to do with racism.
Despite these initial skirmishes, you put that nagging feeling in the back of your head that something wasn’t right about your brother’s new partner to one side and prioritised making Meghan feel welcome in the dysfunctional and odd Royal Family.
Prince William has ended two-decades long friendship with the ITV News presenter Tom Bradby, pictured greeting the Duke and Kate Middleton after they announced their engagement in November 2010
Bradby hosted an ITV documentary in South Africa in 2019 which Harry used to publicly confirm a feud with his brother
Bradby’s ITV documentary in South Africa in 2019 also saw Meghan Markle tell him: ‘Not many people have asked if I’m okay’
She was invited to spend Christmas with you and Kate at your Anmer Hall residence in Norfolk, a decision you supported even though it went against royal protocol.
Discussions soon started about Meghan taking a leading role in your beloved Royal Foundation – the Fab Four was born.
But no matter how hard you and Kate tried, it soon became clear that Meghan had not moved to London to quietly settle into life as a community-focussed royal.
I remember from my reporting at the time that Kate was not happy with the way Meghan spoke to staff at Kensington Palace. Your wife rightly raised the issue and it caused tension.
The infamous bridesmaid dress fitting and Meghan’s failure to accept Kate’s apology for whatever did or did not happen made things worse.
You were also dragged into the sensitive row over which items from the Royal Collection – including tiaras worn by your mother – would be loaned to Meghan.
In the end, following discussions with the Queen’s dresser Angela Kelly, it was down to your grandmother to make the tough call to Prince Harry that made clear, given the royal pecking order, Meghan couldn’t always get what she wanted.
But the damage was done.
You and Kate had tried everything, but fundamentally Harry and Meghan had made a decision that they didn’t want to be on your side. Their narrative as victims of the system was firmly set in their heads.
Prince Harry and Prince William after the traditional Christmas Day church service at Sandringham in Norfolk in 2013
The Duke of Cambridge, Prince Charles and Prince Harry at the Invictus Games competition in London in September 2014
They were increasingly angry you wouldn’t back them in petty battles with the media. Your advisers were, entirely appropriately, beginning the long and sensitive journey of preparing you to be king, and didn’t think your public input would be helpful.
The final straw for you came with the way Harry and Meghan behaved over the Megxit debacle.
You are right to feel it’s unforgivable that they twice tried to publicly jump your grandmother – now 94 – into giving into their ludicrous demands.
The phone calls largely stopped, Harry and Meghan left the country and very open wounds remain.
Before that despicable Oprah Winfrey interview, where they accused your family of racism, you had hoped that matters could be resolved privately over time. The Windsor way, you might say.
There was the possibility of a fruitful reunion to unveil the long-awaited statue of your late mother later this year.
But sadly, it’s now reached the point where you can no longer trust your brother or his wife, largely down to their ongoing manipulation of the American media.
Private conversations with family members have twice been twisted and dissected for US TV personalities Oprah and Gayle King, both friends of Meghan.
You’ve rightly ended your two-decades long friendship with the ITV News presenter Tom Bradby, who you believe has taken sides by becoming a media mouthpiece for Harry and Meghan.
The Sussexes have declared war and are not attempting to start any form of healthy discussion.
The Duke of Cambridge, the Duchess of Cambridge, the Duchess of Sussex and the Duke of Sussex arriving to attend the Christmas Day morning church service at St Mary Magdalene Church in Sandringham, Norfolk, in December 2018
The Royal Family leave Westminster Abbey following the Commonwealth Day Service in March 2020
The Duke and Duchess of Sussex speak to Oprah Winfrey in their bombshell tell-all interview which first aired on March 7
History will show the problem was with Meghan, not you. She has fallen out with most of her close relatives – including her father and half-sister – and no old friends were on the guest list for her wedding.
Her friends are in showbiz now. They’re ready to exploit her for their own gains, be it by securing TV interviews or advancing divisive identity politics.
By contrast, you are going to be king. Your priority is to keep the monarchy popular, not give in to your brother’s petulant tantrums and delusions.
Bowing down to Harry and Meghan is no longer the right thing to do and that’s why you were correct to publicly state at the first available opportunity that ‘we’re very much not a racist family’.
Many old friends of Harry I have spoken to are convinced he will come back to you and Great Britain, but it’s going to take him some time to work out the mistakes he’s made and how he’s let you down.
Until that time, there is nothing more you can do. Harry knows you love him and that you’ll do anything for him if he’s in serious trouble.
It’s painful. But the time has come to stop appeasing your brother. He’ll soon learn millions of dollars and a Californian mansion don’t compare to the unconditional and unwavering love of your blood relatives.