Yanukovych knew Ukraine relied on cheap Russian gas and a plurality of the country but not a majority wanted closer ties with Europe.
His party was formally allied to Putin's United Russia party and eastern Ukrainians wanted closer relations with Russia. His oligarchs were financially entangled with the West and feared Russian competition.
The US cynically manipulated these rival factions to stage a right-wing coup in 2014 that drove a corrupt, yet duly elected president from office by killing police officers and protestors alike.