His party didn't 'turn against him'. Those that didn't manage to flee were under the thumb of the coup regime and didn't want their legs broken.
The pro-EU Maidan protestors were the pretext for the coup. Right Sector & Svoboda - who actually carried out the coup - had no interest in joining the EU. The Ukraine they prefer to live in could never pass the anti-corruption requirements. Now - after eight years - the Ukraine is no closer to joining the EU than landing on the moon.
Once the coup went in: Obama's WhiteHouse made sure that US Aid money - laundered through Kolomoisky's Privatbank - was used to fund the proxy war in Donbass. This isn't your hand in a stream Brother - but men, missiles, tanks and artillery.
Remember that the Svoboda party had only about 8% of the seats in the Rada, but mysteriously held a whopping third of the coup government’s 18-member cabinet.
This included the posts of Deputy President, Minister of Defence and Prosecutor-General. That's the state monopoly of force right there. With enough billions in redirected Aid - and later, direct 'lethal Aid' - the Donbass war that they began could theoretically have gone on for ever.
Wrong on every point.