I can’t help but suspect that the sanctions against Russia by EU and US are more about forcing Ukraine towards EU than about protecting Ukraine from Russia.
If I were Ukrainian, I would trust Russia before EU.
It was and still clear that sanctions won’t affect Russian posture on Ukraine.
The main idea behind it is to bring discord between Russian elites and middle class and start trouble following a pattern seen in Egypt, Libya and Ukraine itself.
Of course if won’t ever work as planned and the middle class, which is the most interested in Russia being associated with the West and doing according to common interest, is factually hit hardest or probably eliminated at all enabling dark forces (under Putin presidency or someone’s else which doesn’t actually make difference) which are interested in widening confrontation without any restriction.
It might get really ugly.
As for Ukraine I don’t think we are in position to lecture them on allegiances. It is up to them but they have to wise up to start with and engage in alliances not purely politically but out of national interest in mind.