The part of Russia that the Russian leadership cares about (Moscow) can't easily be invaded by ground forces from anywhere other than Ukraine. Ukraine is the way that region has historically always been invaded. Ukraine is Russia's achilles heel. So of course they are concerned about who controls it. No, the West wasn't lining up in Ukraine to attack Russia, but these kinds of weaknesses need to be "nipped in the bud".
Also, Russia has been in Sevastopol, their only warm water port, since 1783 (when it was Ukrainian, they were on good terms and Russia leased it). Based on the battle lines I'm convinced Russia wanted a land bridge to that port since the Kerch bridge is vulnerable. Despite what anybody says to the contrary; the battle lines speak louder than words.
I think Russia should stay the fuck out of Western Ukraine. And I expect they will. If Russia ends up keeping everything East of Moldova and South of Kharkiv (the yellow region, see this map in this note: nostr:nevent1qqstl4ahamehgtjeskl9q320ms73ltwzpx7tm3q3z87smg8pvs6snmgpzpmhxue69uhkztnwdaejumr0dshszyrhwden5te0v5hxummn9ekx7mp0qy88wumn8ghj7mn0wvhxcmmv9umrl307) and it stops there, maybe a peace can eventually be had. Russia gets their port. Kiev and Western Ukraine remain an independent sovereign country.
If Russia tries to go further then that, I think NATO will put boots on the ground and escalate massively.