He used to call her “the sister I never had” – turning to her for advice and guidance, and often being pictured sharing a joke together at royal events. In fact, so close was Prince Harry and Kate Middleton’s relationship, he even gave his brother Prince William the engagement ring he’d inherited from their mother Princess Diana, so that his future sister-in-law could wear a piece of jewellery that meant so much to him. And, on William and Kate’s wedding day back in 2011, it was Harry whose pride was palpable as he stood beside his brother, whispering, “Wait until you see her,” as Kate proceeded down the aisle. As far as siblings-in-law go, both Harry and Kate knew they’d struck gold.

Now, however, their bond – though still intact – has been challenged by bad blood and warring factions. After all, it’s no secret that Harry and his wife Meghan Markle’s relations with the royals are at an all-time low, following a series of increasingly pointed attacks they’ve made against “the institution” since they stepped down as senior royals and moved to California. Harry and William’s once unbreakable bond now lies in debris and, according to insiders, the brothers no longer speak. Meanwhile, both Harry, 39, and Meghan, 42, have spoken about the frosty reception the latter received from William and Kate when she married into the family. It’s no secret that – despite Harry hoping that his future partner would turn their trio into a tight-knit foursome – the sisters-in-law have never quite seen eye to eye.

So, where does this leave Harry and Kate? According to sources, the two have still kept things on reasonably good terms throughout the fracas. Indeed, despite the physical and emotional distance between them, they still keep in touch, update each other on their children, and offer one another a listening ear. But now, we’re told, enough is enough. With Meghan keen to put the past – and Harry’s family – behind them, she’s no longer happy to see Kate, 41, and Harry sharing so many so many tête-à-têtes, and now she’s laying down the law: it’s time to move on for good.

“Harry has always found it comforting that he’s still on decent terms with Kate, even when his relationship with William is at rock bottom,” says an insider close to the Sussexes, who were in Germany last week celebrating Harry’s beloved Invictus Games. “Whenever the going’s been tough and he’s landed himself in hot water over the years, Kate’s been there with wise advice and has found a way to smooth things over. It really does speak volumes that, even after everything that’s happened, they check in frequently. Up until now, they’ve kept the dialogue light, which hasn’t been a problem for William or Meghan, but now Meghan thinks this has gone on long enough. Given that William seems as bitter as ever and there’s so much ill-will against the Sussexes that goes unchallenged, she no longer sees what purpose it serves for Harry to stay on good terms with Kate.”

Though it’s hard to determine when exactly William, 41, and Harry’s rift turned into an irreparable fallout, it’s safe to say that momentum has been building for a while. The Sussexes drew the first punch two years ago when they sat down with Oprah Winfrey for a tell-all interview, and took aim at the alleged animosity, racism and lack of support they’d received from the royal family. Since then, they’ve claimed that the Palace “fed Meghan to the wolves” and that William, 41, had left Harry “terrified” during their Sandringham Summit, held to discuss the details of Megxit, by “shouting and screaming” at him. In his recent memoir Spare, Harry claimed his brother had “knocked [him] to the floor” after a heated exchanged sparked by William’s supposed antipathy towards Meghan.

They’ve also had some complaints to make about Kate and her allegedly icy behaviour. In his book, Harry claimed that Kate, 41, had looked “disgusted” after Meghan asked to borrow her lip gloss, and also told her new sister-in-law off for making a joke about her “baby brain.” Meanwhile, Meghan has rubbished claims she made Kate cry ahead of her wedding over a disagreement about Princess Charlotte’s flower girl dress – stating in fact it was the other way around.

Now, Closer understands, Meghan is keen for her and Harry to focus on their future in LA and cut ties for good. Over the past year, they’ve both received some flak and backlash over their continued complaints against the royals and – the way she sees it – it’s time for them to relaunch the Sussex brand in their own right. With a highly-anticipated return to Instagram in the offing, Meghan is keen to ingratiate her and Harry into the upper echelons of Hollywood, and form new alliances and connections in the process with the likes of the Kardashians and Beyoncé and Jay-Z. We’re told that, with Meghan laying the groundwork for a new Sussex chapter, she’s urging Harry to focus on their future and say goodbye to the past.

“Meghan’s put all the royal nonsense behind her in order to focus on their Hollywood prospects – and she wants Harry to do the same,” our source reveals. “Even if he’s not discussing their marriage or intimate details with Kate, she’d prefer it if they only talked once in a while. If he wants to check in and wish her happy birthday or seasons’ greetings, that’s fine. But long heart-to-hearts are where she’s now drawing the line. It’ll be interesting to see how Harry responds.”