The answer was always obvious, but frankly too many people put too much stock into whatever line Putin and the Kremlin gives at any given moment on any given subject and that maybe blinds them to common sense.
Sure, there is a historical connection between the Russian and Ukrainian people, and there are many Russian speakers in Ukraine who historically look east versus west in terms of geopolitical disposition. But we are still talking about a proud people from a sovereign land... one can maybe be inclined to look east without wishing to be invaded by their eastern neighbor. Some arguments seen before the invasion, here and elsewhere, seemed to struggle with this... people may have leanings, but they may have them within the context of a sovereign Ukraine, not within one being invaded and subjugated. Where the friends and neighbors are being slaughtered, etc.
A lot of contemporaneous interviews from people in Kharkiv and east of the Dnieper that I've seen in print or in TV clip seem to back this up - suggesting that very few expected an invasion and that, once it did happen, it was a sin that would take generations for the Russian government to fix, with a prerequisite being the departure of Putin.