I tried to make the analogy with the US tariffs on Switzerland, so that you could finally understand that you cannot negotiate the end of a conflict that was unilaterally started, when the aggressor still thinks it has the upper hand. It is not possible.
Just like the Swiss cannot force Trump to lift the tariffs, and if he is not willing to negotiate, there is nothing they can do about it, the same situation is true for Ukraine and Europe against Russia.
Putin is not willing to negotiate the end of the war under reasonable terms, so there is nothing Ukraine and Europe can do to have peace. Their only option is to fight and increase the pain on Russia, until the Russians are willing to negotiate a just peace, which means withdrawing from the whole of Ukraine, and allowing it to join the EU and NATO.