It's as much up to the west as it is up to Russia. The Ukrainians are stuck fighting a proxy war for NATO here. It's also worth noting that Russia offered negotiations right before Ukraine started their ill fated Kursk offensive. It's pretty clear that neither the Ukrainian regime nor their western sponsors want to negotiate. The real tragedy in all this is that the war could've been over two months in when the negotiations in Astana were happening, but as we now know the west sabotaged them and convinced Ukraine to fight instead.