It's one of those tired old cliches — a product, perhaps, of a society that looks for discord among women — that too often proves true.
The shadow of the mother-in-law looming large over her son's wife, as they build a life together, start a family. The power in that relationship, the fear of never measuring up.
So spare a thought for Catherine, the new Princess of Wales, living in the shadow of Diana, the "People's Princess", her husband's late adored mother whom she'd never met.
After the Queen's death this month, Prince Charles quickly bestowed his former title — the Prince of Wales — on his son William, and Catherine became the Princess.
There hasn't been a Princess of Wales since Diana's death in a car crash in 1997 and Catherine would be well aware of the significance of it holds — for the family, and the British public.
Women's Weekly royal correspondent Juliet Rieden says it's a real endorsement of Catherine's work and her place in the family that her new title was announced by King Charles so quickly.
"There is a pressure that comes with it. But I think that pressure has been on Catherine's shoulders from the minute she married Prince William. The comparison started coming thick and fast even though we were talking about her mother-in-law," she says.
"Catherine automatically stepped into that role of being the most photographed young woman in the royal family. That is the mantle that comes with the Princess of Wales."
Cultural historian Dr Cindy McCreery says the problems during Diana's time in the role has ultimately changed how the royal family would handle the Princess of Wales.
"The number-one message the royal family has learned from the days of Diana is that they must support the Princess of Wales, that they must include her, that she must absolutely be seen and feel to be fully part of the family," she says.
"I think they've done that although, of course, one could then comment that clearly, Megan Markel, and Harry have not felt fully welcomed."
The ghost of Diana
The late Hilary Mantel once wrote of Diana that we "gossip about her as if she had just left the room", despite her death now being 25 years ago.
That icon held on a timeless pedestal bares little resemblance to the 19-year-old woman from an aristocratic family thrust into the limelight.
"The princess we invented to fill a vacancy had little to do with any actual person. Even at the beginning she was only loosely based on the young woman born Diana Spencer," Mantel wrote.
After the break-down of her marriage with Charles, the tabloids were relentless, and when she died in a car crash in Paris, paparazzi were trailing not far behind.
Already a public favourite, her early and tragic death sealed her legacy.
McCreery, a senior lecturer at the University of Sydney, puts that in perspective for today.
"It must be an incredible set of shoes to fill," McCreedy says.
"And, of course, Diana died at age 36. Younger than Catherine is now. And she will, of course, always be frozen in people's memories as his young, beautiful princess and that's a really hard act to follow
"She would be in her early 60s now, but people will never think that."
A title with a long history
For generations, royal spouses have been facing the same challenge.
The title of Princess of Wales has its origins in medieval times, according to McCreery.
"It isn't by and of itself a title that gives the holder any kind of constitutional or political power. It's traditionally given to the wife of the Prince of Wales, being the wife of the immediate heir to the British throne, but that's not always been the case," she says.
"It hasn't of course been held by all future queens because it sort of depends on the situation they were in when their husband became king.
"Queen Mary — Queen Elizabeth's grandmother — was the last Princess of Wales before Diana."
Her eldest son, Edward VIII, wasn't married when he took the throne, but later abdicated to be able to marry the American divorcee Wallace Simpson. His brother, Albert, who was then the Duke of York, became King George VI.
"His wife — who became Queen Elizabeth, the Queen Mother — came to the throne having previously been the Duchess of York because of course, her husband wasn't the Prince of Wales," McCreedy says.
The Queen Consort Camilla, too, didn't take the title, which is another form of baggage for Catherine, says Juliet Rieden.
"Camilla was entitled to that title after Diana but didn't choose to use it. So the title has sort of been on ice for a while," she says.
From bubble to magazine covers
Catherine and William met in 2001 when they were both students at the University of St Andrews in Scotland.
There they lived as housemates in a sort of bubble, protected from media glare by the "gentleman's agreement" Prince Charles had made with the press to give his son a chance at a relatively normal university experience.
That all changed on graduation and Kate — as she was known in the press — and her family became tabloid fodder, in scenes reminiscent of those faced by Diana.
"Before she joined the Royal Family, she was chased down the streets, had issues with photographers just like every young woman who has been connected with Prince William or Prince Charles in the past, or Prince Harry," Rieden says.
"There were terrible stories at the time of photographers hiding out in bushes and jumping out at her to get a reaction to get a photograph with calling her all sorts of things, shouting abuse at her so she would turn around and look hurt."
Things changed once the couple got engaged in 2010, with William giving her his mother's famous engagement ring.
"As soon as she was engaged, the royal household could step in with security and use all of the things at their disposal to try and protect her from the media," McCreedy says.
"That is the big thing that Diana suffered from, the big thing that Meghan suffered from and this is something that Catherine has always had as well on her plate to deal with."
But where Harry and Meghan decided to pull away from royal duties, Catherine has largely taken to the role like a duck to water, despite her middle class upbringing.
"She is incredibly well loved and respected. And I think that her behaviour since the Queen's passing, it's only endearing her more, to the public," McCreedy says.
What will change for Catherine?
Now that she's the Princess of Wales, Catherine's royal duties will increase, along with William's. She will hope to keep working on her favourite issues — including early childhood education — where she can
Supporting family, including the new King, will be a key role. Her three children started in a new school the day before the Queen's death and preparing them for a royal life will soon begin in earnest —and that includes remembering Diana.
"William and Catherine are very keen to make sure that his mother's memory is not forgotten that the children know about her so there's a positive side to it as well, the commemoration of Diana," McCreedy says.
The Wales' children, too, will likely be seen more often.
"She will be keenly protecting her children as much as possible, but also the royal family is aware that there is intense interest in the children and that's a good news story for the monarchy," Rieden says.
Of course, the new title is just the next step in Catherine's journey up the royal ranks. The final — nearly inevitable — step is to the top of the ladder.
When will that be? It's anyone's guess, but her husband is unlikely to have the same long wait that his father did.
"Prince George will have a long wait, but I don't think that William will have a long wait because, of course, Charles is coming to the throne at the age of 73," Dr McCreedy says.
"Yes, his mother came to the throne at age 25, so Charles has had the longest apprenticeship ever as Prince of Wales. I think William will have a very short run in that role."
So, too, would Catherine. And then perhaps this story will repeat, with Prince George's wife, another new Princess of Wales.
