Ironically I can more easily see Germany forgoing territory than France, France had developed its war aims to be the reconquest of A-L, in effect it was the definition of victory. And although Germany had occupied a large swath of France, I do not see keeping it as a certain war aim or definition of victory. Indemnity and colonial concessions can dislodge Germany, France must actually win to get more than a status quo border, Germany must face certain defeat or revolution before it can concede A-L. So I think you need Germany poised for victory but no longer certain as the economy stalls, home front unrest increases and the will to push over the top falters. And you need someone to recognize the moment you do not call a bluff but take the winning you have.
To get at least closer I would have a better Eastern front war and a separate peace from Russia after 1916 closes, likely on some natural line running Riga to Minsk to Kiev, with a more rational armistice that seeks to restore trade and carve out logical buffer states in the Baltic, Belarus and western Ukraine at most. If the USA is not coming we might have a 1917 western front more like 1918 with Germany mounting offensives to achieve victory, Britain will be shouldering the financial burden, France will bleed to defend but the pressure to get peace will be there. Assuming the offensive drives gain to little you can get out of that a plausible stalemate. I think Germany will not see enough food from Russia quickly enough to continue, France will have mutinies if it tries any offensives, Britain will be looking for a way to get out and curb the Germans before they get a run away victory. A very delicate balancing act with all plates spinning. We just need some moderates to push past the now ossified winner take all positions in London, Paris and Berlin.