I think that EU made a mistake (though not complete) when they proposed Ukraine just to sign association agreement.
But in the same time didn't even mention possibility for Ukraine to join EU in the future. The agreement ignores economic realities such as dependence of Ukrainian economy on Russia and impossibility for Ukrainian goods to compete with EU goods. It was one of the reasons that officially triggered present turmoil in Ukraine.
I think that if Western countries really want to see Ukraine drifting in EU direction they would need to provide some large scale administrative and managerial help to Ukraine to help them to adjust to European economic and political standards. And make detailed agreement with Ukraine on which EU market segment Ukraine will be allowed to come in with their goods.