Well, in Baltic states, there
is the cultural gap between Russians and ethnic Estonians, Latvians and Litthuanians in each of the states, respectively. It is not a small one. There are still lots of people who are resident in e.g. Estonia, and were born there, but have no citizenship because they do not (can not, will not) pass the citizenship language test.
The difference to Ukraine is that the Baltic nations grew strong enough already during the final decades of Soviet Union, and they still remembered their pre-war independence.
In 1959, the population of Estonia was roughly the same as in 1939. The difference was that almost a third had been replaced by Russians.
Ethnic Estonians had been first purged by USSR in 1939-1941, then killed by war going back and forth over the country in 1941-1944, and then purged again by Stalin's further repressions until 1950's, by moving people to camps all over the Gulag and killing them there. After that, there was a bit of dual existence, and "Druzhby narodov nadozhnyy oplot!" was rather a less reliable bulwark of friendship than the song was saying.
Then, in 1991, came the singing revolution. After that, many Estonians have migrated to Finland, Sweden, Germany, and other countries, but they send money back home. In exchange, Estonians get guest workers from Russia or Belarus in the same way. Still, it's not that easy for Estonians, as for instance trained doctors and nurses often leave the country after their training.
Ukraine, in contrast, was run by various Russian cronies - the Orange revolution could not build nation -and has had endemic corruption all the time.
What you say about poor nations having bad choices is right as you either leak population or you build a police state that tries to restrain population. Education and eradication of corruption will help, but it's very slow work. I think the Baltic states are showing the way there.