Ukraine isn't in a position to repeatedly turn down all of Russia's demands. Russia has the means to continue pursuing its goals, Ukraine does not. Ukraine broke both Minsk agreements and admitted to never intending on following them, Russia did not.

The reality of the situation is that Russia doesn't have a reason to invade Ukraine in the future if their terms are met, namely the 4 oblasts, NATO neutrality, and cessation of Kiev's oppressing ethnic Russians. People don't go to war without reason, and unless Ukraine has an ace up their sleeves, every day is more dead Ukrainians, Russians, and more favorable conditions for Russia.