Put bluntly, Ukraine is a strategic buffer between Russia and the West, keeping their nukes and armed forces at arm's length. Ukraine didn't like this role, it wanted out, but it underestimated how much this would tip the balance. They moved too fast and against a now-pissed former and powerful ally. Hence the result.
That is, there is a pretty good reason for Russia to do all this even if their methods are painfully crude.
The analogy to an abuser claiming ownership of a battered spouse is becoming incredibly apt.
If you're not a citizen of Ukraine, it's none of your business. Maybe if you didn't keep beating her bloody you'd have a better relationship?
Put bluntly, nukes don't matter, and armed forces are only used to suppress societal discontent. Ukraine sees the regressive authoritarianism Putin creates and didn't like how the pie is cut. Putin is throwing a temper tantrum because he's a dinosaur. He can only look back, and on his deathbed he will look back on a Russia that could and should have been much more.
There is a reason for his party to do all this, but its fear of facing their own failure birthed in greed and paranoia, and not any military strategy in the face of satellites, drones, and hyper-sonic nukes.
That's what Russians say, but if you stop thinking it, it makes no sense.