Russia does not invade in reaction to NATO expansion. NATO expands in reaction to Russian invasions. Notice how NATO does not expand militarily. Not once. Notice how Russia expands militarily, every time.
"Allied leaders also agreed at Bucharest that Georgia and Ukraine, which were already engaged in Intensified Dialogues with NATO, will one day become members. In December 2008, Allied foreign ministers decided to enhance opportunities for assisting the two countries in efforts to meet membership requirements by making use of the framework of the existing NATO-Ukraine Commission and NATO-Georgia Commission – without prejudice to further decisions which may be taken about their applications to join the MAP."
>NATO welcomes Ukraine’s and Georgia’s Euro-Atlantic aspirations for membership in NATO. We agreed today that these countries will become members of NATO.
https://www.nato.int/cps/en/natolive/official_texts_8443.htm
Russia is the only country in the world with a massive formal alliance of major world powers reigned against it. This is because of continued Russian aggression and atrocities going back a long time.
April 2008 [1]
>NATO welcomes Ukraine’s and Georgia’s Euro-Atlantic aspirations for membership in NATO. We agreed today that these countries will become members of NATO.
After the meeting Putin said NATO expansion was a direct threat to Russia.
The Russo-Georgia War was August 2008.
So Georgia being attacked was clearly after attempted NATO expansion east.
In November 2013 the president of Ukraine, Yanukovych, decided to not agree to an EU deal. There were protests in Ukraine which would end in a coup. Some of the European countries try to work out a deal for an election but the protesters aren't going for it. Yanukovych then flees the country.
The new government is very pro West / EU. What then happens in Ukraine starts making anti-Russian moves like removing minority (Russian) language laws.
Russia then attacks Crimea in February 2014.
Again, Russia only attacked after Ukraine was attempting to work out a deal with the EU and after they showed they would use force (the coup) to get it.
Don't get me wrong. I am against Russia attacking both Georgia and Ukraine, but it seems quite clear that Russia only attacks after they start getting too cozy with the West.
[1] https://www.nato.int/cps/en/natolive/official_texts_8443.htm