Ukraine is a sovereign state and can apply and join whichever club it wants to join. More ex-Soviet states joining NATO was based on political decisions of sovereign states and not "the puppetmaster USA pushing to the east", which is Kreml propaganda.

IIRC in the 90s/00s they were talking about Russia joining NATO, too. After 9/11 Putin offered their well-meant help. NATO and Russia were meeting regularly in the past three decades and guess what, Russia left this meeting. Plus, NATO was always very careful arming NATO states near Russia in order to not provoke them. You cannot put this on NATO's card.

Edit: Even after annexation of Crimea, the EU (esp. Germany) tried to calm down Putin by negotiating a piece treaty between Ukraine and Russia and buying even more (cheap) Russian gas.