PARIS — Two days after he took office as France’s president, Emmanuel Macron flew to Berlin. It was May 16, 2017, and France and Germany needed a reset. Joined at the hip, the two nations cannot make Europe work if they don’t work together. Mr. Macron had been elected to transform France, and he was convinced that real change in his country would happen only through better European integration.

Hope was in the air as the young, ambitious but untested French president met Angela Merkel, the stern three-term German chancellor. Ms. Merkel quoted the German poet Hermann Hesse: “A magic dwells in each beginning.” Ever the realist, however, she cautiously added, “Charm lasts only if there are results.”

Two years on, the results are nowhere to be seen and the charm has given way to exasperation. When Ms. Merkel and Mr. Macron met on the sidelines of a Berlin summit on the western Balkans, on April 29, their talk was kept to a strict minimum — 15 minutes. Asked at a news conference about the French-German relationship four days earlier, Mr. Macron answered in unusually blunt terms. He openly admitted for the first time that France disagreed with Germany on Brexit strategy, energy policy, climate change, trade negotiations with the United States — and the list could have been longer. Though he chose to stop there, he vowed to voice his differences firmly for the sake, he said, of “fruitful confrontations.”

Mr. Macron went on to suggest that “the German growth model has perhaps run its course.” In his view, Germany, having made belt-tightening reforms that were right for its own economy, had fully benefited from the imbalances created within the eurozone; especially hard hit were the Southern economies like Spain, Greece and Italy , for which austerity was bitter and destabilizing. These imbalances have worsened, Mr. Macron pointed out, and they now “run counter to the social project” he supports.