That is not what happened. Ukraine elected a leader (with the help of Paul Manafort, who Putin paid for his efforts) that lied about his intentions to join the EU. In fact when he was in power he did an about face on his stated goals and stopped the process of getting into the EU. When he was deposed he fled to Russia - the country that put him in power in the first place.

Basically, Putin subverted Ukrainian democracy by helping to get a puppet elected. Ukrainians did not like that.