"Yanukovych promised agreements with EU". Yes, he ran on signing an agreement with the EU, but when he sas the "fine print" he realised he couldn't do it. Why? Because he would have had to take on enormous debt and :"restructure" Ukraine's economy - i.e., cut pensions, cut subsidies, get rid of labor unions (which Zelensky has already done) and generally accept EU austerity in return for IMF loans. It would have been like Russia under Yeltsin. "I cannot do this," he said, "it would be political suicide".

Putin simply made Y a much better offer.

And yes, people were upset. But the demonstrations were peaceful until the Right Sector started fomenting violence, and then when the Nazi snipers started shooting everyone, it was easy for the US forces to seize control, and Victoria Nuland could see that her friend "Yats" could become PM.