Ukraine has its President Zelensky. The European Union is a union of 27 nations, each with its head of state, a Prime Minister, President or other officer, and the European Commission which sits atop the EU has its President of the European Commission, Ursula von der Leyen, and the current President of the European Council, António Costa.
Why then are all the media, the headlines and opinion pages (and your statement above) all intent on making President Trump the responsible party for "ending the war."
Given the EU is at least 100 million more in population than the US and, of course, nearer to the war, why is not some one (or more) of these dignitaries leading, and "serious about ending the war," rather than passing the buck onto President Trump?
Many here seem to take his comments at the UN to indicate he is walking away from the conflict. I seriously doubt that, as he has made a personal commitment to ending the war. He also realizes that simply walking way is not in US interests, even if he clearly expects Europe to bear the costs (as they should).
At the German occupation of the Saar, the Anschluss and at Munich either the French or the British but never both were agreed to threaten war to stop Hitler. And neither by itself felt strong enough to act alone.
Europe has a much larger population and is far richer than Russia, but is not actually unified despite the pretensions of the EU.
None of them individually are prepared to take strong actions if needed to confront Russia without US backing.