Well that's because western Ukraine was Ukraine before Gorby redrew the lines, most of 'modern' eastern Ukraine was western Russia, and Kiev seems to sit pretty close to the dividing line.
So it makes since that the pro-Russia faction of Ukraine is mostly in the east, because there are people their who remember when it was western Russia, and Gorby didn't ask their opinion when he redrew the map.
It's like all subtly, nuance, and historical context disappear when it means not treating Russia as an evil empire and not trying to reignite/continue the Cold War.
Russia isn't perfect and has the blood of the airliner on it's hands due to what their rebels did, but the Ukrainian gov is corrupt and seem ok with literal neo-Nazi's in their military. Plus what started this whole clusterfuck was what amounts to a NATO backed coup in the Maidan, because we could not accept that a country could prefer to be in Russia's sphere than in NATO's. We could not stop trying to push NATO east, and it backfired massively on us.