Easiest POD for this is if the Kaiser says no way to the Zimmerman Telegram and orders an end to unrestricted sub warfare. He orders that German subs attack only ships flying Allied flags OR ships that fire on them first. Simultaneous to this, the Kaiser releases a statement (in newspapers, on radio, etc) that he does not want war with the US and urging American citizens to resist efforts by their leaders to drag them into Europe's conflicts.
At the same time, CP fights a holding action on the Western Front, and throws everything at the Russians. While funneling money, intel, and all other possible support to the Bolsheviks.
IMO, with this POD, Wilson can never get the public opinion behind him for a declaration of war. The Russians collapse, Treaty of Brest-Litovsk happens, and CP throw everything at the Western Front. With no prospect of US relief, public opinion in France and UK begins to tilt heavily towards a negotiated peace.
An interesting side to this is Italy ( as they were only in the war for territorial ambitions) maybe sees the writing on the wall and asks for an armistice with the CP. The Kaiser leans hard on the Dual Monarchy to accept, eager to send all troops at France. Emperor Charles I agrees, and all CP strength hits France.
French morale goes POOF ( as they were already having to pull cavalry off the front lines to suppress peace movements) and the government flees south, declaring Paris an open city. Germans take Paris, and the Kaiser publicly states that any German soldier who mistreats the people or property of Paris will be publicly hung. The French sue for peace, public opinion in UK turns against the war strongly. A sort of idea like " What in the hell are we fighting for in France if the French don't want to keep fighting?"
PM Lloyd George's government falls, and King George V breaks precedent by publicly decrying " this boondoggle of a war that my people no longer want. I stand with them." Liberal party is swept from power, and the Tories ask for an armistice with the CP. The Kaiser agrees, and the war is over.
Some knock-on effects from this
a slowly democratizing strong German state in Central Europe for the rest of the century
communism penned in to a basket case nation with a strong enemy to its west
Uk remains a strong naval power, calling a great portion of its fleet back to home waters to defend against any possible German moves ( which never come because Germany is content to be a land empire in Eurasia)
Austria-Hungary adopts a more federal system ( as the new emperor intended in the OTL) and is backed by Germany in its efforts, remaining stable as it reforms
the Ottoman Empire endures for some time yet, spending most of the next few decades suppressing Arab nationalism, with German backing
with two militaristic empires as its open enemy, Islamic extremism is strangled in its cradle
the United States remains committed to the Monroe Doctrine and spends the 20th century solidifying its control over the Americas
Japan carves an empire out of East Asia and the Pacific ( this may eventually lead to war with the US if cooler heads don't prevail)
nobody ever hears of Adolf Hitler
All in all, a better world than the OTL, imo