Remaining polite, then, our Russian colleagues are of the opinion that some things are true, when in reality, as verifiable fact, those things are not true. Since they are unlikely to be that mistaken, the polite conclusion is that Russian leadership, and their enablers, are liars. Liars, liars, pants on fire. They have shown themselves to be wholly untrustworthy, as evidenced. This has been repeatedly demonstrated... with all due respect.
The price of certain 'peace plans' is too high. Better to fight.
It's not just one voice, though...
For anyone calling for negotiations, what is the practical basis? Take, for example, Zaporizhzhia Oblast. Is it part of Ukraine? Ukraine and the International Community say yes. Putin says no. Putin hasn't signalled any readiness to say anything other than no, yet. What is the practical middle ground between 'yes' and 'no?' Where is the probabilistic fuzziness between those two states? It's a legit question on my part. There may be a third way that I'm not seeing.
Another example, related to annexing those regions is Putin's strategic need for a land bridge to Crimea (and, let's face it, Sevastopol, because it's not like Putin is overly concerned with Crimean Tatars). Ukraine and the Internationa Community say he can't have it. A peace plan that doesn't grant him the land bridge doesn't fulfill one of his strategic needs, anyway. So, what is the middle ground between 'need it,' and 'can't have it?'