If Russia's spring offensive fails, Russia will be headed towards collapse. It simply does not have the economy or military to keep fighting for very long.

Suggesting it will not pursue reparations or human rights violations against Russia in exchange for the return of all its territory costs Putin nothing. NATO would need to step in an offer to provide Ukraine humanitarian aid while Ukraine rebuilds. Ukraine would also need to be admitted into NATO to eliminate the risk of future wars.

Putin will find one or more scapegoats to execute claiming he was misled. As long as the army stands behind him, he will retain power.

Putin should realize by now, if not, he will by this summer that the longer the war continues, the massive economic power, superior logistics and military hardware advantages of Ukraine's military courtesy of 50 nations supplying Ukraine will slowly grind down both his army and economy without which he is a dead man.

Superior weapons and eventually a larger army (Ukraine will be able field a bigger army than Russia within the combat zone) means Russia is less than a year away from needing to sue for peace. That will be more dangerous for Putin, then pulling out now.

Between islands claimed by Japan, land claimed by China, land claimed by Finland, and land seized from Poland after WW2, Russia has a lot of enemies, and a weakened army raises major concerns especially in the east.

Putin is all about Putin. If Putin does not act quickly to secure a peace, he may likely become a casualty of the war. Zelensky's best strategy to end the war is make clear Ukraine will abide any peace that restores its territorial borders and not participate in any attempt to orchestrate regime change in Russia, while at the same continuing to inflict losses on the Russian army at an unsustainable rate.