I ask you this question as you appear to have a high, yet sensible, perspective on the situation, "what difference does it make now whether Ukraine becomes a member of NATO", since the West is so involved already in a prolonged conflict. I suppose my answers would be:

PRO: We provide the additional muscle to bring Putin to his knees, including embargo of Russia's Black Sea fleet, air superiority over Ukraine (all without attacking Russia proper which might trigger WW III)

CON: We prolong conflict and deny peace prospects while Ukrainians (and Russians) suffer, while possibly triggering WW III anyway.