This bears repeating: Russia's foreign policy has been exclusively one of pressuring and bullying smaller nations into submitting to its will. United States, for all its imperialism and warmongering, understands the value of having allies, countries with mutually beneficial cooperation. And so does China, who tries its best to have a web of countries which will support its geopolitical goals and gain something in return.
But not so with Russia. For Russia doesn't barter. It doesn't negotiate. It doesn't care about you or your welfare. It doesn't try to establish a mutually beneficial relationship based on trust and mutual goals. All Russia does is threaten, and outright invade you if threats aren't enough.
Think I'm exaggerating? Fine, but how to explain that each and every one of Russia's neighbors, almost without exception, feels threatened by Russia and joins anti-Russia alliances at first opportunity? Why is that? Why does everyone in their vicinity end up fearing Russia and adopts explicitly anti-Russian stance? Let's see:
Ukraine - outright invaded by Russia. Not much to add here.
Moldavia - has problems with its territorial integrity due to pro-Russian separatist in Transnistria. If Russian invasion of Ukraine succeeded, likely Moldavia would be next in line.
Georgia - also invaded by Russia, due to latter supporting pro-Russian separatist regions (noticing a pattern yet?)
Estonia, Lithuania, Latvia - former Soviet republics who bailed out as soon as possible and joined NATO at first opportunity. At present day, they are (along with Poland) the most hawkish among European countries with regards to anti-Russian sanctions and supporting Ukrainian war effort.
Poland - was invaded or partitioned by Russia like 7-8 times in last two centuries. Everything it did since the invasion of Ukraine could be summed up as one giant "fuck you" to Russia.
Kazakhstan - recently felt the need for China to publicly state it supports Kazakhstan's territorial integrity. Gee, I wonder whom exactly do Kazakhs feel threatened by?
Finland - one of not-that-many European countries with obligatory military service (one of commonalities among many Russian neighbors) whose entire military strategy seems to be "let's be ready if Russians every decide to attack us". After decades of neutrality just to appease Russia, it finally decided enough is enough and officially petitioned to join NATO.
Sweden - oh, look. Another country in Russian vicinity who seems to think joining NATO is in its best interest. I wonder why that is.
Surprise, surprise - there's is a clear pattern here. Every Russian neighbor (with the exception of its lackey Belarus and China which to too powerful to bully) doesn't like Russia, for some inexplicable reason. And while historical grievances certainly can play a part here, by itself they're not nearly enough to explain this near-universal bad reputation Russia has in it vicinity.
After all, countries have the ability to bury the hatchet and at least try to build future based on peace and cooperation. USA threw two atomic bombs at Japan - nowadays these two countries are trading partners and geopolitical allies. Finland has spent much of its history being under Swedish rule - at present day these two seem to have good relationship and wanted to join NATO together. Enmity between Germany and France lasted for almost a millennia (culminating in Nazi occupation during WWII) - just years later these two cooperated to found European Coal and Steel Community (precursor to EU).
These things happen, but somehow they don't happen with Russia, the main difference being that latter still behaves in militaristic and imperialistic manner to this day, with zero concern for its neighbors territorial integrity. Every now and then I hear about some Russian politician or journalist casually discussing which neighbor to invade next, like some spoiled kind in candy store who thinks all this candy if free for taking. "After Ukraine is over, let's de-nacificate Poland next" ; "Let's take border regions from Kazakhstan" ; "Let's support Transnistria separating from Moldavia" and such.
Oh, yeah - the point was about NATO expanding east, at the expanse of Russia's presumed sphere of influence. With above in mind - small wonder why nobody want to be in Russia's sphere of influence, for all it brings is permanent danger of being bullied or invaded (exhibits A to J above). Russia seriously needs to rethink its foreign policy, for this one doesn't seem to bring them much good. The proposition that one should not join NATO out of fear of Russians feeling threatened has it entirely backwards: the correct thesis is Russia will be a threat to you unless you join NATO.