London (CNN) As 2018 unfolded and details of how Brexit might ultimately play out became clearer, political differences that have existed for years between the United Kingdom's four nations were dragged into the open. Bluntly, Brexit has shone a light on the fact that the foundations holding up the UK had been crumbling for some time.

The two greatest risks to the union are splitting Northern Ireland from Great Britain, as the Brexit Withdrawal Agreement with the EU proposes, and a second referendum, which would legitimize the calls for a second independence vote in Scotland.

The movement in the UK's politics and resulting divisions is nicely illustrated by the last eight years of its voting history.

Let's take the 2010 general election as a starting point, in which voters opted for a coalition between David Cameron's Conservative Party and Nick Clegg's Liberal Democrats. These two centrists looked like a safe pair of hands at a time of turmoil in the immediate aftermath of the 2008 global financial crisis.

Over the five years of the coalition, austerity measures were introduced that made most politics junkies certain that Labour would win back power under its then leader, Ed Miliband.

But a shock result in 2015 saw Cameron win a majority in Parliament. Scotland voted for the pro-independence Scottish Nationalist Party in huge numbers. After the failed Scottish independence referendum a year earlier, the general election result was a clear sign of just how wide the gap between England and Scotland had become.

Fast forward past the Brexit referendum and Cameron's own exit to Theresa May's 2017 snap election for more clues. Many voters in pro-Brexit areas of England snubbed her in favor of Labour's Jeremy Corbyn -- who at the time had an unclear position on Brexit, though much of his party is pro-Europe. She lost her majority, but strangely picked up votes in Remain-supporting Scotland, despite her party backing the very definition of a so-called hard Brexit.

Britain's Prime Minister Theresa May leaves from 10 Downing Street on December 17, 2018.

Clearly, the British public is divided -- and that division is especially acute in the politics of the four nations.

In England, the UK's wealthiest and most populous city, London, stands in contrast to the rest of the country.

It is from London that the campaign for a second vote that could ultimately stop Brexit is being driven. But it was English votes that carried the victory for Leave. This creates tension not just in England, but in the union at large -- the politics of the English are the most influential in the union and can often dictate policy that affects everyone.

In the case of Brexit, that means Scottish remainers feeling as though the English are dragging them out of the EU against their will. Alarmingly for unionists, recent polling showed that English Conservative voters (officially called the Conservative and Unionist Party) would be happy with the union breaking up in exchange for a good Brexit.

The division is more obvious in Scotland. The SNP would clearly like to push for a second independence referendum and rejoin the EU as an independent nation. Meanwhile, Scottish Conservatives would clearly prefer a softer form of Brexit to protect Scotland's economy while keeping the union together -- something about which they disagree with their English counterparts.

In Northern Ireland, the devolved National Assembly has not sat in nearly two years after the power-sharing agreement that allows both unionists and republicans to be involved in government collapsed.

Despite this, the Democratic Unionist Party holds the balance of power in Westminster and is currently one of the biggest obstacles to May getting her Brexit deal through Parliament.

They believe the deal ignores their most important demand: no friction between Northern Ireland and Great Britain. "We do not want a hard border, we believe there are many ways of resolving it," the DUP's Emma Little-Pengelly said to me of the Irish border issue. Instead, she believes that May and the EU's solution "aims to ensure no checks at all on the Irish border between two sovereign states by creating 68 new checks between Great Britain and Northern Ireland."

It must be worrying for the DUP that both those wanting May's deal to pass and hardline Brexit voters are so happy to see their red lines rubbed out for the sake of getting the job done.

Traffic crosses the border into Northern Ireland from the Irish Republic.

One thing seems to have been forgotten by politicians in all this: some people in Brussels speak English. The UK's chaos has been watched with astonishment by EU officials.

"It's still not clear what the UK wants," Guy Verhofstadt, Brexit coordinator for the EU Parliament, told CNN. "I hope the deal agreed finds a majority. If not, then MPs have to work together to find a compromise solution on a future relationship. Whatever the choice, we need a withdrawal agreement to be agreed to avoid a disastrous no-deal outcome."

It's still not clear what the UK wants. Guy Verhofstadt

Loathe as many in Westminster will be to take advice from a former Prime Minister of Belgium, he makes a solid point. Wild politics is not a good enough reason for a nation as important as the UK to fall into a black hole of its own creation.

The good news is that as things stand, both main parties believe the union should be preserved. It shouldn't be beyond the wit of our elected officials to forge some cross-party unity on a matter they claim to care so much about.

As Brexit reaches its apex, perhaps the minds of the political elite will sharpen and we will all start to see a way out of this hellscape. They need to make the public care about the union, or frankly, it's only going to crumble further.

If that doesn't happen, then the UK as we know it will have to continue to exist on life support.

And if we don't take this moment to fix the union between the four nations, then distressingly few will be in mourning, should the switch get flipped.