Nonsense. They have existed since the time of Peter the Great and were exacerbated under the expansionist rule of Catherine the Great. In the last century, Stalin's horrific
Holodomor (deliberate famine in Ukraine; literally means "hunger death" in Ukrainian) and
Great Purge made those problems far worse. The Ukrainian SSR voted in 1991 to secede from the Soviet Union, not Russia. The Russian Empire no longer existed at that time, although everyone also knew that the Soviet Union was a wink-wink extension of the earlier Russian Empire. Gorbachev made the mistake of thinking that the Soviet SSRs would all want to remain in the Soviet Union dominated by ethnic Russians, so he allowed the so-called republics to vote on accepting a liberalized version of that union. The SU recognized the independence of all three Baltic states in September 1991, and Ukraine broke away in December of that year.
Ukraine was never an independent nation-state prior to 1991. It never existed as an independent, sovereign entity before that time. The territory was always under the rule of some other country, whether Poland-Lithuania, Turkey, the Golden Horde. One could just as easily argue that Imperial Russia
liberated Ukraine from foreign occupiers who never should have been there in the first place.
But either way, neither Peter the Great nor Catherine the Great invaded Ukraine, since there was no independent state of "Ukraine" to invade, as the territory was ruled by other countries. Peter invaded Sweden (which is also how Russia ended up in the Baltic region, which was also always under some other country's thumb), and Catherine invaded Turkey and annexed territory from the Polish-Lithuanian Commonwealth.
Also, it should be mentioned that Russia's primacy over Eastern Europe didn't really become solidified without the help of certain other Europeans. For one, Napoleon, who invaded Russia, which fought back, drove him out, then found themselves in a prestigious position as a victorious great power at the Congress of Vienna. You could also look at Prince von Metternich, who was influential at that Congress and established the European order at the time, which meant that Russia ruled in the East, gaining Poland, the Baltics, and Finland in the process. Imperial Russia's control over Ukraine had already been established and recognized even before that time.
The Holodomor was part of an overall famine which affected the entire Soviet Union, and it's rightly considered an atrocity blamed on Stalin and his government at the time. Stalin implemented a collectivization program in his first 5-year plan. Stalin wanted to accelerate industrialization of the country, which was where his focus actually was. Another aspect was the fact that Stalin's political power base and hold was in the cities, but the Bolsheviks' control over the countryside and rural areas (in both Ukraine, Russia, and all the other territories) was a bit tenuous and not fully solidified. Stalin ostensibly saw that as a threat against his power. The NEP also allowed for the rise of Kulaks who were getting rich, and Stalin apparently wanted to take them down a few notches and show them who's boss. Like in this scene here:
Of course, the farmers would not accept the state-imposed prices, so they essentially boycotted the State. They ate as much food as they could and destroyed the rest. They killed their livestock. They ate their seed grain so they had nothing left to plant with. The horrific famine then ensued.
But regardless of what view one might take, the conflict in question was between a Party/State of multiple nationalities versus Kulaks and other farmers of multiple nationalities. It was never a matter of "Russians vs. Ukrainians" as some might try to paint it. It was "Russians vs. Russians" and "Ukrainians vs. Ukrainians" as much as anything else. Civil wars are always complicated in that way.
The Purges were a completely different matter, as that was largely internal to the Communist Party itself and its internal apparatus. Stalin was able to keep the party machinery intact, and it still kept on rumbling along for a few decades after his death. But his successors weren't quite so paranoid or murderous (although that didn't make them choir boys either). Khrushchev and Brezhnev both came up through the ranks under Stalin, so they would have been sympathetic to those in the party who would have feared Stalin. As long as people did their jobs, kept their mouths shut, and didn't make waves, then they'd be left alone. Like the US, they had a huge military-industrial complex, and the Red Army was the biggest in the world. They were more geopolitically focused and started to expand their influence across the seas. The U.S. leadership considered them to be a grave threat to America and our way of life, so we were committed to stopping/restraining their possible expansion wherever they could.
By 1991, the original reasons for the Cold War and animosity (largely stemming from the time of the World Wars) no longer seemed relevant. Even the Holodomor and Great Purges were a thing of the distant past, just like slavery in the U.S. and the British occupation of India. They allowed Germany to become reunited again, since they felt reasonably confident that they would never turn Nazi again.
It is truly unfortunate that the newly-formed independent governments could not come together more amicably. None of them were "Soviet" or even "Communist" anymore, so what was the problem? And why couldn't the West be a bit more empathetic and understanding to the situation they were facing? The Soviet Union did not surrender to the West. They mutually decided to break up of their own accord. Technically, all of the Soviet Republics had the right to secede, which was guaranteed in their Constitution, but apparently no one wanted to secede prior to 1990. But once they did decide to secede, it was done legally. The hardliners tried to prevent it with a coup in 1991, which brought Gorbachev down, but the coup fizzled out and suddenly Yeltsin was in there. Kind of an odd, unlikely series of events.
Still, once the Soviet Union was no more, the hardliners locked up or dead or otherwise neutralized, and all of the Republics peacefully transitioning to becoming independent, sovereign states, there didn't seem to be any immediate reason for any conflict - and for the most part, there hasn't been, up until recent years.
en.m.wikipedia.org