There has been a power struggle ongoing in Ukraine for some time.
The President in 2014, Yanukovych fled Ukraine to Russia, The Ukrainian parliament voted to remove him, because he "had effectively resigned". Yes, it is clear the US, under the Obama regime, was involved.
How much Yanukovych was under the control of Russia is debated.
Yes, Ukraine is famously corrupt, but I doubt it is less corrupt than Russia.
From my limited contacts (I have a friend who travels to Ukraine often) it appears the people of Ukraine understand the government is corrupt, and wish to rectify the situation.