Of course, anyone who has spent 5 minutes digging in to the history of Ukraine - it isn't hard to understand why. Russians have raped and pillaged what we know as Ukraine for centuries, but it grew to horrific levels under the Soviet Union - with Stalin's Holodomor Genocide setting the tone for the Russian treatment of Ukraine/ethnic Ukrainians ever since.
Reasonable estimate: 10,000,000 Urkainians dead in that genocide.
Even the Chornobyl disaster - was handled with the same utter disdain for Ukrainians.
Ukrainians have watched their hopes of both independence from Russia, and their sovereignty constantly attacked - by Russia, both overtly through policies and threats (and blatant lies from Moscow), but in slightly more covert means in Russia's manipulations of Ukrainian elections, maffia-like extortion and racketeering for nearly a decade in Crimea to destabilize it then set off red flag violence to give Russia an "excuse" to invited and annex right in the wake of the Maidan Revolution in Kyiv (which was a revolution against a Russian puppet).
There are a lot of layers to Ukrainian hate of Russia - and while not all is "right" or morally justified - anyone who cares to understand history, cannot help but sympathize.