BRUSSELS — So here we are at the supposed Brexit cliff — a political crisis and diplomatic crisis rolled into one — and I have a confession. I’m thoroughly bored by it all.

I suspect I’m not alone.

For those beyond Brussels and London, maybe just starting to tune in, here’s some advice. Let go of any illusions that this drama is about trade protocols, residency rights or the status of the Irish border. The histrionics going on in the United Kingdom aren't even really about its impending departure from the European Union — or about Prime Minister Theresa May’s tenuous attempts to cling to power.

Brexit is the story of a proud former imperial power undergoing a mid-life crisis. The rest of the world is left listening to Britain’s therapy session as they drone on about their ex-spouse, the EU: When will they stop talking and just move on?

The promise of Brexit at the time it narrowly passed in a national referendum in June of 2016 was that it was a way for Britain to feel big again — no longer hectored by the EU bureaucracy in Brussels, no longer treated as just one of 28 members in an unwieldy confederacy.

The U.K. simply doesn’t seem to know how to play the game of give and take needed to negotiate with a far larger partner.

"Britain is special," the Brexiteers assured British voters, who cast their ballots accordingly.

The last two years have revealed something different: For the first time in modern history, Britain is small. Having sailed into the 20th century as an empire, the U.K. spent the second half of the century shedding nearly all of its colonies — and as a result much of its economic and military might.

But that was ok, in part because the U.K. — a permanent member of the U.N. Security Council and a nuclear power — had a close ally in the United States. But even more importantly, it was alright because, just as decolonization was drawing to an end, the U.K. joined an emerging economic and political power: the EU.

The U.K. finally overcame French objections and joined the bloc in 1973, seven years before it lowered the Union Jack in its last African colony and more than a decade before it struck an agreement with China to hand over Hong Kong.

Ignorant about its leverage and ignorant about the EU, the U.K. is coming across as clumsy and caddish.

Britain’s imperial history and 45 years of membership in the EU — where London was a dominant voice — is why it is struggling to conduct diplomacy as the middling power it is now becoming. Accustomed to issuing colonial diktats or throwing its medium-sized weight around a medium-sized pond, the U.K. simply doesn’t seem to know how to play the game of give and take needed to negotiate with a far larger partner.

It is perhaps because of this history that many people in the U.K. are so awfully uninformed about the EU. Its political and journalistic classes are simply unused to having to consider the opinions of others.

I can’t say I’m surprised. From various perspectives — now as a journalist, formerly an adviser to both the U.K. government and the EU, and always a citizen of the Commonwealth — I’ve been immersed in Brexit and Britain’s identity complex for years.

While many Brits have strong emotions about the EU, they rarely have a strong understanding. I feel like a kindergarten teacher every time I speak on the issue.

It is fashionable to blame an irresponsible U.K. media (including the country’s most famous sometime-journalist, now leading Brexiteer MP Boris Johnson) for stoking misunderstanding about the EU for decades. Long before Macedonian troll factories and Russian bots there were the editors of the Sun tabloid newspaper.

But what about the millions of people who consumed those fibs and the spineless politicians who avoided the hassle of correcting them? We blame Greeks for blowing up their economy and hold accountable big-spending governments for saddling future generations with excessive debts. Britons don’t deserve a free pass: It’s time they reckoned with what they sowed through 45 years of shallow EU debate.

It is Britain’s unique ignorance that makes Britain so boring. Ignorant about its leverage and ignorant about the EU, the U.K. is coming across as clumsy and caddish.

Nothing tells the story better than the sad stop-start diplomacy of Theresa May. The prime minister is an appropriate leader for a shrinking Britain — one without a clear or consistent vision, whose efforts at both navigating Brexit and her own political survival seem driven by awkward improvisation.

London’s demands are simply unrealistic, as anybody with more than a passing familiarity with the EU can tell you.

Her frequent mad dashes across Europe underline how the U.K. lost the negotiation before it had begun. May flies across the Continent with fanfare, but her trips are always driven by domestic pressures — not a desire to find common ground with those on the other side of the table.

Meanwhile, EU negotiators have laboriously and quietly toured every capital, building up their united front before the talks started. Chief negotiator Michel Barnier could find himself locked in a thousand black cars, and it wouldn’t matter: He’d step out smiling every time.

Britain’s political contortions are symptoms of an almost willful lack of understanding: The U.K. doesn’t know what it wants from the EU, and doesn’t really know what it wants from getting out.

For decades, as one of the EU’s larger — and more troublesome — members, London secured itself special deals inside the EU. It won rebates from its budget contributions and opted out of the euro and Schengen rules governing border checks. It now feels entitled to similar treatments as it leaves.

Today Britain wants things it already has (frictionless trade with the EU), without continuing to pay the price other EU members pay to have it (the legal, economic and political constraints that come with EU membership).

London’s demands are simply unrealistic, as anybody with more than a passing familiarity with the EU can tell you.

Balancing competing interests is difficult enough for individual countries. Look at U.S. Congress, the German federal system, or even the mighty French presidency trying to cope with the yellow vest street protest movement. Doing the same across 27 countries is even harder. Negotiations take time, and any sudden sharp policy change has the potential to disrupt the EU’s equilibrium.

The deal on offer is the best London is going to get — simply because it is the best Brussels is going to be able to offer.

And yet, cheered on by two ex-U.K. Brexit negotiators who barely bothered to show up in Brussels and negotiate, British politicians are lining up like whiny children to demand the remaining 27 EU countries make amendments to the Brexit deal.

Britain has a lesson to learn. What a global power can pass off as “exceptionalism,” for a medium-sized country simply comes across as ingratitude.

Ryan Heath is POLITICO’s political editor.