While in principle I do get the idea that a negotiated peace is preferable to a situation where the two parties in a conflict simply fight themselves until one side physically cannot, I do not see a way in which that can reasonably be done in the case of this conflict without one side being beaten militarily, because the goals of each side are not comparable. Russia has been trying to annex territory from Ukraine, but as far as I have seen, Ukraine has not sought to take land from Russia (if you take only the current phase of the conflict, one might suggest that they are seeking to retake Crimea, but as you yourself pointed out, the conflict itself has been ongoing for longer than the current large scale war has been going on, and as such, even if the Ukrainians managed to take it somehow, that would not represent the addition of new territory not in their possession before the conflict started). The problem this presents is that, if one were to negotiate a "white peace", that is to say, just put the border back to how it was before the conflict started, then that effectively represents Ukraine accomplishing pretty much all of its major goals and Russia none of it's own. As such, Russia has no particular reason to accept this, unless physically forced to by virtue of military defeat, which would kind of defeat the point of a negotiated settlement in the first place as that would simply represent a Ukrainian military victory anyway. But on the flipside, ceeding any of the disputed land to Russia represents a situation where Russia wins- maybe not anything like as big a win as they would like, but they would in that scenario have started a large scale war (regardless of how exactly the conflict itself began, Russia did take the step of turning it from what it was into a full-scale war, by invading Ukraine), and then ultimately gained territory from it, which is exactly the sort of precedent that we've already established needs to be avoided. What then, is left for such a settlement to be?