The EU on the other hand is under existential threat from Russia so they (we, actually as I'm French) really ought to do something serious to help Ukraine not only stabilize the front line and wear down Russia, but win this war.

But because we underinvested in defense for decades (because the Western Europe couldn't imagine a conflict was possible with their biggest trade partner, and because eastern Europe was too keen on trading political influence inside the EU to the US in exchange for security guarantees against Russia without having to build a capable military on their own) we ended up in 2022 with little capabilities to really help Ukraine.

And because of the obsession with public spending and debt reduction, countries refused to seriously invest seriously in their industrial capabilities to supply the Ukrainians with a war-changing amount of ammo and other assets. (the fact that South Korea alone was able to give more ammo to the Ukrainians than the whole of EU in 2023 is a sad joke really).

I can't really blame the US, they played their own interests while minimizing consequences for them (and that's also why they wanted to avoid escalation in priority). But I do blame European leaders, including my own president, for not taking this matter as seriously as they should have. (For a full 10 month in 2023 Les forges de Tarbes, France's main production of 155mm shells, has been stuck with no way of producing anything because they couldn't pay their suppliers because they lacked liquidity to do so, this was utterly ridiculous and should have been solved with a single phone call. But nobody in charge bothered, for almost a year…)