Borderline personality disorder can be tough to spot if you know a person only socially. It's estimated that 6% of the population has this disorder. Most of these people date, marry, and have children, so it's not an uncommon experience to commit to someone in a relationship, only to discover that suddenly the person flies into a terrible emotional upset, angry or crying hysterically when the partner has no idea what upset the person, or knows, but it's something most people would never get so upset over. Partners or spouses find themselves loved one minute and demonized the next. With BPD, tumultuous, up-and-down relationships and difficulty holding a relationship together become an unsettling new normal as partners settle down and become more familiar with one another. Sadly, this happened almost as soon as Prince Charles proposed to Lady Diana Spencer in 1981, and it became worse as the marriage went on.

Having been raised by someone with the illness, I can’t tell you how many times my mother could hold it together in order to appear sweet, charming, lively, and adorable in public, only to abuse me in private. I remember feeling desperate as a child, because I knew if I told, no one would ever believe me. Prince Charles had too much class to ever expose the rages, crying, and fights in the royal household in an interview, but even if he had wanted to, he probably recognized that if he told the truth, people would think he was lying. The kind of intense suffering and acting out he would have described simply did not tally with our images of the kind, beautiful Princess Diana who graced public events and the newspapers every day, always ready with a smile, a hug, or a joke. Eventually, however, all the facts of what happened made their way into newspapers and books, and it became clear that Princess Diana met many criteria for a BPD diagnosis.

BPD sufferers run the gamut between being so symptomatic, like Marilyn Monroe or early 80’s supermodel Gia Carangi, that the casual observer could tell they had emotional problems, to being more high-functioning and able to hide their emotional distress for long periods of time in public. Princess Diana tended toward the more high-functioning end of the scale, but even she had her public breakdowns where the cameras caught her crying.

Those with BPD tend to show more symptoms the more you are with the person and the better you know them. Often from a difficult family background, they tend to weave fantasies about how a romantic relationship will make them feel as loved as they always needed to feel, but never did.

But, at the same time, borderlines have only a hazy sense of who they really are as a person, and they have a deep sense of self-loathing and shame. Each sufferer has a long history of never feeling good enough. They enter a relationship expecting to be slighted—as Diana certainly was when she became aware her fiancé was having a tough time saying goodbye to his longtime love, Camilla Parker Bowles.

This kind of situation would be difficult even for the most solid soul, but Diana, already needy and sensitive to any kind of rejection, believing from childhood that she simply was not good enough, could not think clearly about the situation at all. All she could do was react. Binging and purging, raging, and episodes of self-harm are common ways borderlines fly into intense emotion and react.

Most of us, disliking our babysitter, wouldn’t put pins in her chair. Most of us, having a disagreement with our stepmom, wouldn’t push her down the stairs in a rage. (Both of these things, Diana admitted to doing.) Most of us, faced with our husband wanting to go out riding when we hoped he would stay in with us, wouldn’t become so upset we throw ourselves down a flight of stairs. Emotions in BPD are biochemically heightened, so that a small disappointment to you and me can feel as traumatic to a borderline as if someone’s just died.

This is the difference between Diana and a person without BPD. Her well-publicized bulimia was a symptom of the BPD, not Diana’s whole problem. Diana believed , when she acted out in response to whatever had made her upset, that anyone would react this way. But, the reality is that to live with someone who breaks down in uncontrollable tears and suffering, when you have no idea what you did to upset the person, or when you are just trying to leave to go to your job or to some outing you’ve had planned for months, is highly distressing and upsetting. This was daily  life in the Wales household.

Sadly, little was known about BPD in the early eighties. In the early 1980’s, pockets of knowledge about BPD existed, where expert therapists could make slow but excellent progress with a patient who was dedicated and had good family support. Rachel Reiland is one example of a BPD patient who made a full recovery in the 1980’s. But therapist Marsha Linehan had yet to write her seminal book on BPD, and her definitive treatment for the illness, dialectical behavior therapy, had yet to be invented. The explosion of good books about the disorder that reached the public in the 1990’s and 2000’s hadn’t happened yet.

Prince Charles had never heard of the illness, and it’s quite possible Diana’s doctors hadn’t, either. Diana often lied about her symptoms, not sharing with her therapists that she had bulimia, which made proper diagnosis difficult. And without full knowledge of what you are dealing with, marriage to a person with BPD will be miserable at best, and impossible at worst.

Diana and her family simply didn’t have access to competent help. These days, the best treatments for BPD include help for the family as well as the patient. If Charles and Diana could have received modern information and treatment then, their story might have had a different ending.

If Charles had understood his wife had a diagnosable, treatable mental illness, no doubt he would have educated himself about it instead of seeking comfort from Camilla. If Charles, the Queen, and Prince Phillip had had access to full information about the illness, no doubt the family would have pulled together, the Palace would have insisted that Diana cooperate with treatment, and she would have gotten the kind of support she really needed. What a story that would have been!

The fact that the Palace completely missed any information about BPD in the 80's demonstrates how little it was known and understood then. If a correct diagnosis eludes the Prince and Princess of Wales, two of the most privileged people in the world, the right information must be muddled, indeed. A doctor who knew about the illness might have screened Diana for it more carefully.

As it was, Diana’s outbursts and mood swings made the marriage impossible.

As a child, I witnessed my mother’s relationships with both my father and my stepfather, so I can imagine what Prince Charles was dealing with. My mother had incredibly low self-worth and a very negative opinion of herself. (Witness Diana’s joke that she was “thick as a plank.”)

My mother was a lower functioning BPD. When my father died suddenly, my mother had never gotten a driver’s license or managed a checkbook herself. She believed she was stupid and had no confidence in her ability to do these tasks of daily living. (Compare this to Diana, who remained terrified of having to do her public engagements for years, even though she had performed so successfully at so many that it was clear the public loved her. She took a very long time to develop the confidence she should have from her many successes.)

My mother often blamed my father for “not letting” her have her own money and “not letting” her drive, when, many years later, I witnessed my stepfather offer to teach her to drive the pickup (my mother said no), and my great aunt told me both she and my father had offered to give my mother driving lessons. That my mother looked back on this and lied about it is typical of BPD. (In Diana’s case, even though we have evidence Prince Charles was concerned about her and tried to teach and encourage her, Diana went on the record stating that he never did.)

This is only one of many distortions Diana put out about the Prince over the years. Having little sense of self, image becomes everything, and Diana's attention to how she came across in the papers is legendary. She used to scrutinize the photos of herself in the papers every day, and then call up the journalists she trusted to try to put a positive spin on any story that showed her in a bad light.

With BPD, a person feels worthless, but doesn’t want to feel this way, so they have a tendency to back down from a challenge and then blame someone else for making them do it. They tend to make the facts fit their feelings, instead of being honest about facts and remembering them clearly. Then they get upset, and when a borderline is upset, be prepared for a lot of extreme, dramatic behavior.

A person with BPD is less able to calm themselves down, think clearly, and control themselves than the average person. Screaming, crying, and rages ensued, ending up in scenes like Diana crying in the bathroom while Prince William shoved her tissues under the door, begging her not to be sad. Someone without BPD could notice how they were upsetting their child and pull themselves together. Diana could not. So the things that upset Diana the most made family life more and more unbearable.

Prince Charles found himself completely at a loss, and probably felt very distressed at what was happening. It wasn’t only Diana who needed someone calm and comforting to come home to; as in any marriage, Charles did, too. That is a main reason most of us get married. With someone so volatile at home and no way to make sense of the situation, he needed a sounding board and someone to lean on. As is so often the case with BPD, Diana drove Charles back to Camilla, even though it was the last thing she wanted or meant to do. This phenomenon is well known and one of the great tragedies of BPD.

This chain reaction of perfect disasters blew into the perfect storm that was Charles and Diana’s marriage. It was always destined to end unhappily. Charles ended up running from the marriage, looking for comfort and shelter, and Diana did, too, seeing several men secretly both during and after the marriage.

It's very common for a relationship to devolve in this way when BPD is a factor. In the 2010's, information about the disorder is more widely disseminated and easier to find, but finding the right therapist is still difficult, and in the States, at least, expensive to pay for.

If your relationship is starting to sound like Charles and Diana's, BPD Central is an excellent place to visit, full of practical, easy-to-understand for BPD sufferers and their families alike.