The war just cannot go on: Russia is adamant that it must have control of the Eastern edges of Ukraine to defend itself from NATO expansion. It will win; without negotiations now the country will be destroyed and it will take a generation to rebuild. Western support for Ukraine in the military resistance and resolve to regain the territorial integrity of what was Ukraine in at the turn of the Century and even at 2014 with the annexation of Crimea by Russia is not sustainable in the medium let alone the long term.
Ukraine will be on its own. So the sooner it realises that it is highly foolhardy to allow your country to be devastated in the name of geographical integrity the better for Ukraine. If negotiations do not take place now both Russia and Ukraine will get poorer with nothing gained from the war.
Ukraine must reduce its ambitions to regain all the territories lost to Russia and cut its losses from the year long conflict. Russia must make its ambitions clear as whether it still wishes to control all of Ukraine.
There has to be cease fire to enable negotiations to begin: who will broker the ceasefire. It must be a neutral country, non aligned to NATO with no bilateral relationships except for trade development: no military relationships.