If Putin stops fighting and withdraws his army, the war is over. If the Ukrainian army stops fighting, Ukraine as a people and nation comes to an end.
Ukraine as a nation may or may not come to an end. Maybe Putin recognizes that Russia can't digest the whole thing and it would be too much of a problem. But peoples have a way of surviving through defeat and occupation. What is the whole history of Eastern Europe but an illustration of that?
And what if Putin wants to stop fighting, but doesn't want to give up the territory? This is going to come down to something short of complete victory and complete defeat.
Did Ukraine's people exist in the 1980s when they were part of the Soviet Union? Or did they not exist then?