What actually happened in Ukraine was that the president went back on his promise to try to work towards join the EU (possibly due to threats from Putin) and so

What actually happened in Ukraine was that the president went back on his promise to try to work towards join the EU (possibly due to threats from Putin) and some young Ukranians organized a protest on social media because they saw the EU as the only hope for a bright Ukrainan future (if you want to know why just look at the economy and corruption levels in former communist EU countries compared to Ukraine) and the President as going back on his word and throwing it away. Instead of considering their points or even trying to ignore them he tried to suppress the protests with extreme violence and ridiculous anti protest laws people thought might lead to dictatorship like in neighboring Russia or Belarus. The Ukranian people didn't like this and the protests grew and grew and grew. The EU and US encouraged the political opposition to make a compromise with the President even if it was unsatisfactory. But then the police who has been fighting the protesters got cold feet that the president would throw them under the bus in the deal, so they disappeared and the President decided to do the same. Since he abandoned his country and his post the legislature had no choice but to remove him from office including many from his own party. A couple of US politicians voiced support for the people protesting for their rights against a corrupt and increasingly authorian leader, I see why they did it but how is that relevant to any of this? Also Poroshenko wasn't in any way installed or a puppet, he was elected by Ukranians in an election that was fair and free followed by another fair and free election which he lost in a landslide. That's democracy. Poroshenko may have not been the best leader but he was tons better then Yanukovych and it was pretty hard to run Ukraine even before Russia invaded.