I think the answer is in the past. How Russia and the Ukraine interacted throughout history before the coerced formation of the Soviet Union. I do not think Putin wants a Russian empire with world dominance per se. Putin wants a strong Russia nobody should mess with. Russia and the Ukraine should form an economic alliance then the territorial disputes would take care of themselves. Either way, it is not the USA's cup of tea and should stay out of it altogether.
Those lands which make up contemporary Ukraine belonged to various countries in the past. In the middle ages there began to form so-called Getmanshchina – a state which consisted mostly of the central part of contemporary Ukraine. In the middle 1600-s there were a war between Getmanshchina and Poland, and the former had to apply to Moscow for the help. Moscow did provide the help but demanded in return that Grtmanshchina be part of the Moscow Tsardom with a right of broad autonomy. But time passed by and the rights of the autonomy were being ceased more and more. At least, Catherine the Great abolished the autonomy altogether.
In next centuries such names as Ukraine and Ukrainians were forbidden in Russian Empire. Instead of them there were used names Malayia Rossia (Little Russia) and Maloross (Little Russian).
It was a brief answer how they interacted. Though, I am not a historian, so any remarks are welcomed. But remarks not from Russian trolls, but from those who is really interested in history.
About economical integration.
The Russians are always arguing that the Ukrainians are lazy, greedy, hypocrites, live (and have always lived) at the expense of Russia, and the like. So let’s give Russia a favour and pull Ukraine away from it. )
Well, thanks for your answers anyway.