After nearly half a century of close-knit cooperation and more than three years of wrangling and acrimony, Britain has parted ways with European Union (EU). Post-World War Two European integration has received a stunning blow.

Parting is always painful and so is the uncertainty that comes along. EU has lost a prominent member state for the first time and the divorce has opened up many unanswered questions.

The United Kingdom accounts for about 15 per cent of the EU’s economy and is its biggest military spender, and the City of London is the world’s international financial capital.

But the United Kingdom’s economy is worth about $2.7 trillion while that of the EU is currently worth $18.3 trillion.

While the divorce is a blow to EU prestige, the remaining 27 members remain by far the bigger commercial power.

Though in actuality, very little will change during an 11-month transition period, doubts persist about what lies ahead.

Will British firms be able to trade tariff-free with the EU? Will British students be able to go on European academic exchanges? Will British police be able to arrest suspects who have fled to the EU?

Prime Minister Boris Johnson has set an end-of-year deadline to secure a deal after negotiation all this and much more. But how smooth the process will remain remains unknown.

Johnson’s government hopes to negotiate a deal with the EU alongside a free trade agreement with the United States. That’s also likely to be contentious.

Brexit opponents have their reservations. Many of them believe that Brexit is a folly that will weaken the West, shrink Britain’s global clout, undermine its economy and even lead to a more inward-looking and less cosmopolitan nation.

Such fears cannot be easily written off as unfounded.

June 23, 2016, the date of Britain’s referendum on EU membership, feels like a long time ago. The referendum, which split voters 52% to 48%, showed up deep divisions and triggered soul-searching about everything from secession and immigration to empire and modern Britishness.

So severe was the Brexit meltdown that allies and investors were left astonished by a country that for decades seemed a confident pillar of Western stability.

Britain was never a wholehearted EU member. Its resistance to many EU projects over the years is well known. It also refused to join the single currency or the Schengen free travel area.

The exit idea gradually gained strength within the Conservative Party, which has a wing of fierce “Euroskeptics.”

Former Prime Minister David Cameron eventually agreed to hold a referendum, saying he wanted to settle the issue once and for all.

But things took a dramatic turn. Since the 2016 vote, the UK has held fractious negotiations with the EU that finally, late last year, secured a deal on divorce terms.

European Union leaders have already warned that the more Britain moves away from EU regulations, the less access it will have to the bloc’s huge market of around 440 million consumers.

European Commission president Ursula von der Leyen’s comment drops a clue about the impending path: “We want to have the best possible relationship with the United Kingdom, but it will never be as good as membership. Our union has gained political impetus and has become a global economic powerhouse. Our experience has taught us that strength does not lie in splendid isolation, but in our unique union.”

That’s not as good as saying everything is fine.