Russia is a Mafia. Just selling gas 'honestly' is not enough. They must break the buyer's legs to get him into debt, so that he will spend the rest of his life paying it off, even if he's hardly using any gas at all.
Hardly using any gas? Ukraine has heavy industry, using gas. All heating id done using gas. All cooking is done using gas.
"break the buyer's legs to get him into debt" - that's just stupid! Stop paying your electricity bill for a few months and see where it gets you.
But I thought they wanted to join the Soviets, oops I mean, the "Eurasian Economic Union"?
In Ukraine there is a love/hate relation to Russia, coinciding to the East/West partition. Plus, the Western part puts a little love over the hate base when the gas is delivered cheaply, and the borders are open, so they can find work in Russia.