No one "left" anyone. Eastern Europe had a right to self determination, which was infriged upon by the soviet block. Blame the soviet block. Western Europe coming in and "spreading democracy" would have been a disaster.
It's easy for you to say, now that the west has won the cold war. At the time, Western Europe was simply either with the US or trying to find a third path, neutral and not involved in the cold war.
It is the responsibility of Eastern European to revolt and make a country for themselves, not anyone else's.