The only side to blame for invading Ukraine is Russia. Literally no one else. That's not to say US hasn't had involvement in Ukrainian politics - I'm sure they did. The responsibility for the invasion still lies 100% with Russia.
Claiming Ukraine sister nation for Russia is not exact same, but similar to claim Israel sister nation to Iran, or Japan sister nation to China.
The U.S. is 10x more powerful than Russia who is 10x more powerful than Ukraine. Russia falling for the trap of a quagmire on their border is not the fault of the U.S.
And adequate person might notice, U.S. is practically on the border, between European and Latin American parts of world.
Practically, the same as Ukraine on the border, between Europe and Central Asia.
And this geographic situation is very important, on border you could not be really neutral and weak, you must choose one side and be strong enough to be on this side or you will be divided to sides by some external force.
And Russian behavior is very typical for Central Asia. Absolutely nothing extraordinary.
Read and count, in how many coups involved Russia (unfortunately you may need to use google translate from country of Democracy and free market): ru.wikipedia.org/wiki/Советская_республика
And yes, I don't think "Soviet republic" as Democracy, because I've seen USSR and it's pseudo-elections without choice. What they are, you could see in good film Bridge of Spies with Tom Hanks - literally, gangs occupy country and supported by some Communists country - caught on such things Russia, Iran, Venezuela, China.
Ukrainian elections after 2004, ALL considered democratic, if you don't hear from your sources.