And then there is the vexed, complicated problem of Britain and its exit after more than 40 years, which few European countries either expected or wanted. Like the guest at a party who overstays his welcome, Britain and its internal psychodrama are getting on the nerves of its European partners, who fear further economic and political uncertainty to add to the already unhappy mix.

The British government and the ruling Conservative Party are deeply divided about what kind of relationship they want with the European Union, apparently having forgotten that the other 27 nations must unanimously agree to any new deal, and what Britain wants is not entirely the point.

The frustration for Brussels is that it cannot force Britain to act. It has to wait for the government to trigger Article 50, which begins a two-year negotiating period for exit. While many European leaders had wanted Article 50 to be invoked immediately after Britons voted to leave on June 23, they agreed to the March timetable.

That remains Mrs. May’s stated goal. But the High Court decision — which the government is appealing to the Supreme Court — has created the potential for months more delay, as well as the prospect that Parliament might lay down negotiating parameters that could make the talks even more difficult.

Mrs. May’s few public statements imply that she is leaning toward a “hard Brexit,” emphasizing control over immigration and Britain’s borders, even if that forces the country to leave Europe’s single market and hurts the economy. But the pro-European forces who make up a majority in Parliament, emboldened by the court ruling, may now have the means to soften her stance enough to keep Britain in the single market.

That would mean compromising on immigration, which is anathema to hard-line supporters of Brexit in her party and right-wing nationalists. The haggling could go on for some time.