Yeah, the Ukrainian people threw out Yanukovych multiple times for being a Russian puppet.

Yanukovych argued in favour of economic modernisation, increased spending and, initially, continuing trade negotiations with the EU. He pledged to remain non-aligned in defence policy. However, his years in power saw what analysts described as democratic backsliding,[10] which included the jailing of Tymoshenko, a decline in press freedom[11] and an increase in cronyism and corruption.[12] In November 2013, Yanukovych made a sudden decision, amidst economic pressure from Russia,[13] to withdraw from signing an association agreement with the EU and instead accept a Russian trade deal and loan bailout. This sparked mass protests against him that ultimately led to his ousting as president.

How or where is the US involved in this? and why would they care?

Or you know Occam’s razor,

pressure from Russia clearly indicates they want Ukraine and are upset that their puppet was thrown out by the people.