I treat Russia as an ordinary liberal democratic state led by ordinary human people with rational self-interested motives

It means I judge them by the same standards I’d use to judge any similar state with a similar political and economic system in similar circumstances.

Do you? So let's say the UK decided to funnel weapons in to Ireland to restart the Troubles and then sent tanks in to annex Donegal. Would you be similarly opposed to arming Ireland against a much larger and better-armed neighbour? After all it'd hugely expand the UK's exclusive economic zone at sea and significantly reduce the length of the border to defend against Ireland, it seems beneficial for Britain. I don't know about you, but I'd hope someone would back Ireland up in that situation.

If you’re an American as I am

I'm not

the 2014 coup of Ukraine

Good job Ukraine has had two elections since then huh

the ongoing war on Donetsk and Luhansk

It is interesting how so many of Russia's neighbours have pro-Russian separatist movements that always seem to have Russian backing

prohibiting a negotiated end to the ongoing conflict

What leverage do you think Ukraine's supporters actually have to prevent a peace? They'd stop supplying it weapons? Well you apparently want them to do that anyway. Presumably that's because you think Ukraine can negotiate peace without being armed enough to fight Russia. In which case these peace-blocking supporters have no leverage with which to block peace.

Of course they have even less leverage over Russia, which could end this war tomorrow by literally just fucking going home

You’re not some unbiased neutral observer

I didn't claim to be unbiased in the slightest. I am openly pro-Ukraine here. Because I'm generally against countries invading their neighbours and killing hundreds of thousands in order to annex territory, no matter how beneficial it might be to the invader.

Absent continuous US intervention for over a decade, this war never happens.

This is literally just American exceptionalism for people that don't like America. Other countries also do things. Russia has a track record of exactly this kind of thing.