1. The eastern regions' locally-elected authorities never chose to separate from Ukraine. They were, however, violently overthrown by armed Russian-integrationists after local administration buildings were stormed by those same integrationists, who, incidentally, had a conspicuous number of connections to Russian government. Whether these connections were Russian in nationality, ethnicity, identity, or other technicalities is irrelevant. There is a straight line between LPR & DPR and the Russian government.
2. The eastern regions did not ever want to join Russia. A majority of each region of the Ukrainian SSR voted for Ukrainian independence in 1991, which was recognized by all involved parties as well as internationally. All polls for years have shown that reversing this vote and joining Russia is widely unpopular.
3. In contrast to the armed separatists, Euromaidan activists did not participate in an armed rebellion, but in protest on the town square after Yanukovich made an unpopular move against the intentions of the elected Parliament, capping off dissatisfaction which had been brewing for years, where they were shot by government security forces. Yanukovich lost almost all his support, signed an agreement with the opposition
which included the provision that he would remain President for the time being. He then fled anyway, and the Parliament removed him from his post in absentia in a legal impeachment motion.
Everything that happened to Yanukovych was legal, and he left his post
on his own initiative (because he understood his political career in Ukraine was already over).
And Yanukovich's corruption was not secret, ambiguous, or moderate in scale. He had a massive mansion estimated to cost $1 billion & a
huge estate, with his own galleon, an ostrich farm, a gold-plated chandelier, lakes of swans. People saw it all with their own eyes after Euromaidan, there are plenty of pictures. Meanwhile the state treasury was nearly empty when he left. Needless to say this is unlikely to be supported by his Presidential salary.