BRUSSELS — Angela Merkel, the German chancellor, was uncharacteristically furious. At a dinner to celebrate the 30th anniversary of the fall of the Berlin Wall, she huddled with President Emmanuel Macron of France, who had just given an interview in which he cited the “brain death” of NATO and wondered whether its commitment to collective defense still held.

Mr. Macron had also been the sole leader to veto the start of lengthy membership talks for North Macedonia to join the European Union, despite Skopje’s having done everything Brussels had asked of it, including changing the country’s name.

“I understand your desire for disruptive politics,” Ms. Merkel said. “But I’m tired of picking up the pieces. Over and over, I have to glue together the cups you have broken so that we can then sit down and have a cup of tea together.”

Mr. Macron defended himself, saying that he could not simply go to a NATO meeting in London in early December and pretend that the United States and Turkey had behaved in the collective interest in Syria.