Putin believes in spheres of influence for great powers. He would prefer that Ukraine was part of Russia but a separate Ukraine that was aligned with Russia would have been acceptable, just as he finds the political situation in Belarus acceptable. (However that ship has sailed for Ukraine now, unfortunately) What Putin, and many Russians too, find unacceptable is a Ukraine which is aligned with the west, because he finds the idea of a military base so close to Moscow intolerable. (In this context Vlad explains, with many examples, that Putin is completely obsessed with the speed of nuclear weapons in particular)
I have no special insight on the feelings of the Russian people. I find the explanation of a Vlad Vexler informative because he grew up in Russia, understands Russian, follows developments in Russia closely, and is a political scientist/philosopher by training. He gives a fuller explanation of the situation in Russia in the video below, including what Russian people think, and the limited ability to curtail Putin. His explanation of the trembling of Russia’s security chief before Putin was particularly incisive—and terrifying for its implications for Putin’s intentions and the inability of those around him to alter his course.