EU membership was never feasible. Russia is too large population-wise, it would have threatened franco-german leadership of the EU. The EU, as it was back then was hanging in a delicate balance, where France and Germany usually had to agree on something to get things done, but other countries could form blocks of convenience to push their own demands through (eg. UK, Nordics and the Netherlands on fiscal discipline, or the Baltics, Visegrad and countries from the Balcans on immigration). France and Germany would not have wanted to lose that much influence, Poland would not have wanted to be between Russia and Germany again (politically speaking), and hatred of Russia runs rather deep in countries of its former empire.