Russia is basically calling the West's bluff that they won't use nukes to enforce their ideology and Russia won. Everyone wants to talk big until it comes time to actually enforce words.
> I don't think the West ever threatened a nuclear response to Russia's invasion of Ukraine.
I think so, too, but I also think it’s likely that, through silent diplomacy, there was a clear message “if you nuke the Ukraine, there will be a response in kind”.
Without the USA, it’s hard to keep that message, though. Neither England nor France can respond in kind to a tactical nuclear weapon, as they don’t have any.
Russia, however, repeatedly threatened a nuclear response to the West's military assistance to Ukraine. Those were the bluffs that got called.