It must have been a doozy of a night.
In early 2016 Prince Harry, Princess Eugenie, Sienna Miller, Margot Robbie and Cara Delevingne crammed into a photo booth at a Notting Hill bash for what must be one of the most epic party pics in recent history (it was sponsored by vodka brand Ciroc which might explain the, um, unbridled nature of things).
Here was Hollywood glamour colliding with not one but two bona fide HRHs who all looked like they were having the time of their A-list lives.
While the appearance of a prince and Our Own Margot in the photo booth was a bit of a headscratcher (who'da thunk it right?) seeing Harry and Eugenie painting the town red together made perfect sense.
There has always been a certain kinship and closeness between the royal duo. It was the princess who introduced Harry to his former girlfriend Cressida Bonas and according to some reports also connected him with designer Misha Noono, who is rumoured to have set him up with her bestie Meghan Markle.
Fast forward four years and the picture could not be more different.
Harry's boisterous party boy ways have been replaced by a new found penchant for proselytising about environmental issues and living some curious simulacrum of civilian life in Canada.
So too has his relationship with Eugenie and her sister Beatrice fractured, according to new reports, with a series of recent events straining the once close Wales/York bond.
Last weekend, Harry and Meghan put out a lengthy statement which portrayed the couple's frustration with recent, post-split events. The statement covered a variety of issues that have been the subject of swirling speculation including the future of Harry's military patronages, their ability to term themselves "royal," their styling as His/Her Royal Highnesses along with their intention to get jobs.
However, one particular line seemed particularly pointed: "While there is precedent for other titled members of the royal family to seek employment outside of the institution, for the Duke and Duchess of Sussex, a 12-month review period has been put in place."
So, just who are these "other titled members of the royal family" who head out every day to earn a crust?
Beatrice and Eugenie are the obvious prime candidates.
The inclusion of that one sentence has been interpreted as a thinly-veiled pot shot at the York sisters. While the sisters might be HRHs, neither undertake official duties, receive money from the sovereign grant or have official protection thereby making them trotting off to pursue their 9-5 dreams far less problematic.
There is another issue brewing, too. Invitations for Beatrice and her fiance Edoardo Mapelli Mozzi's May 29 wedding are yet to go out however the Sussexes' attendance is already reportedly causing headaches.
If Harry and Meghan don't turn up it will look like him turning his back on his family, however, if they do suit up and join the crowd of 150 friends and family cramming into St James' chapel their very presence could very well overshadow the bride and groom's big day.
A friend of the Yorks has told the Telegraph: "Of course Harry and Meghan will be invited but it is up to them whether or not they choose to attend. The trouble with Harry and Meghan is that they think they are bigger than the institution. It's such a shame things have turned out like this."
There is some unfortunate precedence here. Harry and Meghan told the royal family they were expecting a baby at Princess Eugenie's October 2018 nuptials which left the bride "hurt", according to reports. Also, Harry only, reportedly, stayed for only one drink at the night-time reception before leaving (party Harry would surely be horrified by such abstemiousness).
Intra-family squabbles are hardly new, especially for the Windsors.
Prince William and Prince Harry have been widely reported to be feuding for more than year. The relationship between Prince Charles and Prince Andrew has reportedly been strained ever since the heir apparent unveiled his plan for a slimmed down monarchy which did not include the Yorks.
However, cousinly bonds have always been strong in the royal family. The Queen is close to her cousins, especially Margaret Rhodes, while in 2018 Mike Tindall, married to Princess Anne's daughter Zara, revealed that the royal cousins have a WhatsApp group.
Likewise, Catherine, Duchess of Cambridge, has regularly been photographed laughing with Autumn Phillips, who is married to Prince William's cousin Peter (that said, the Phillips are currently in the process of divorcing).
These relationships among the younger generation of Windsors have always seemed particularly strong. No matter what other sibling conflicts or internecine battles have raged behind palace walls, the Yorks, Cambridges and Phillips' routinely put on a commendable show of unity and genuine affection.
"The overwhelming feeling is just one of sadness," a source close to Zara has told the Telegraph.
"She is incredibly fond of Harry and just feels so sad about what has happened. That's how they all feel."
At a time when there is so much upheaval and change going on inside the royal family – moving countries, new marriages, maybe even babies – it is heartbreaking that these cousinly bonds have frayed to such an extent.
For Harry on a personal level, this represents the loss of a support system and network of people who truly understand the stresses and strains of the truly mind boggling, bizarre life of a royal.
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• Prince Harry and Meghan Markle may snub Princess Beatrice's wedding - reports
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Exacerbating that loss is the fact that recent months must have been some of the most difficult and tumultuous of his life (the death of his mother Diana in 1997 notwithstanding). He has made some dramatic life changes and anyone, royal or not, needs their loved ones at these moments. Adrift from his family reinforcements, so to speak, it is hard not to wonder how he is faring emotionally.
More broadly, for the royal family as an institution and brand, this fracturing of ties is a blow. This is a family that prioritises unity and familial bonds and that in turn is central to their image. Take the annual turnout on the Buckingham Palace balcony or their mass church walk on Christmas Day. Those sorts of images of a happy clan are PR gold.
Practically, any iota of drama also detracts attention and sucks oxygen away from the valuable work various Windsors are doing (it's not all opening the Chelsea Flower Show you know). The last thing post-Brexit Britain needs is to see the nation's internal divides reflected back to them in their royal family very publicly unravelling.
Prince Harry arrived back in the UK on Wednesday to begin his last series of official engagements as a working royal. Photographed at a Scottish train station, the 35-year-old looked dour and downcast. Maybe he needs to jump on the Windsor cousin WhatsApp group, it looks like he could do with some good cat memes.
This article was first published on news.com.au.