Putin will stop this war only if you can make/force him to. He is not going to wake up one morning and says "let's end this". It is either a decisive Ukrainian battlefield victory, or Ukraine outlasting Russia in a war of attrition/ causing economic collapse and some kind of internal coup happens (e.g Russian Revolution). Neither is likely at this point.Zelensky doesn't drag this on. Putin does. Zelensky and the Ukrainian army is only trying to stop the Russian invasion of their country. Zlelensky has no possibility to stop the war unless he capitulates. Putin on the other hand, can stop the war tomorrow if he wanted.
Ukraine might feel aggrieved that as a victim, it has to compromise, potentially giving up terrorities to Russia, the aggressor, which effectively rewards the aggressor action but that is unfortunately, the reality today (keep fighting but neither Russia or Ukraine has to capacity to truly win)