The US interferes with other countries when it wants to, for various reasons. It doesn't need the approval of everybody else. It has and still does supply weapons and other support to all sorts of people that are freedom fighters or terrorists, depending on your point of view.
Ukraine historically has had strong links with Russia...long before the US even existed, and long before the Russian Revolution of 1917.
https://en.wikipedia.org/wiki/Kievan_Rus%27
EU/Ukraine discussions have been going on for decades, Russia acting the way it has more recently isn't just a matter of not wanting them to join the EU.
I'm not condoning any of it, but I understand that media everywhere likes to promote certain views. What we got here was probably what you got - the western view of Russia being really bad and the Ukrainians being good people (during the 1940s Ukrainians were some of the most ruthless soldiers in the world on both the side of the Nazis [80,000 or more volunteers by 1943 I believe] and the Russians [something like 4-5 million]). A civil airliner gets shot down? Oh that was the Russians as it was a Russian made weapon that did it (an assumption made before having any definite proof).
The EU has acknowledged for a long time that Ukraine has undemocratic processes, is unstable and needs to clean up its act.