This antipathy largely precedes Donbass war; the whole existenz of the Ukraine as independent state had been totaled by its second president Leonid Kuchma to three (in Russian) words: UKRAINE IS NOT RUSSIA (the title of his book https://imwerden.de/publ-11870.html ), while Ukrainian rightwing nationalists fought on Chechen side in Caucasus wars of Russia during 1990s. But yes, on February 24 Putin gave the world a masterclass of how to lose the war simply by starting it first.