The premise that Putin just doesn't want NATO on the border with Russia is just another Putin lie. He wants to annex Ukraine, just like Georgia, and take Russia back to it's "lost glory". It's about expansion. First he claimed it was because Ukraine applied to NATO. Then he claimed it was about "nazis", then he claimed it was about some people on the border of Ukraine and Russia. It's simple. Just like 1939 simple. Russia has goals of expansion, control, and power. Bet on it. Putin is Stalin in a nice suit. He's old school KGB.
FYI, I have no problem with differing opinions. I completely understand the reluctance to spend money on Ukraine. I'm skeptical as well. And no fan of Zelensky. He's just not as problematic as an expansion seeking KGB Putin.
It's no single thing. Every single thing we hear is Propaganda, ~every~single~thing. Regardless, NATO creep is a huge part of what's happening. And we had a sort of deal, and we sort of reneged. Kinda like plausible deniability for all. Either way, Putin or any other Russian leader would be out of their mind to be A-OK with NATO sitting next door.... especially when 1/2 the population of the main force behind NATO screams Russia every time someone farts in an elevator. Not to mention, Nuclear Deterrence is still a thing, not matter what ~anyone~ says. And remember, those people over there... they think in Centuries that go back MANY before our happy little corner of history was a passing dream. There's far more to this than Russia wanting Ukraine. Russia see's Ukraine AS Russia. But hey, that doesn't fit the narrative.
There's is a huge gap in far-Western thinking... we simply don't understand the history over there, and it's massive. It's the same reason why/how China is making us look like fools. It's only partially their doing, we're real good at doing it all by ourselves.
We all live in our own box. As difficult and uncomfortable as it is, I still try hard to step outside of mine as often as possible.