In fairness, EU leaders have acted. Germany has literally undertaken historic alterations of it's legal ability to spend on current and future defence, France has offered to wrap Europe in it's nuclear umbrella, the EU has passed epic spending bills to support the growth of the European defence industry, etc. The EU is actively discussing military integration between nations and there's public appetite for it.
Shit just takes time. I get the reaction, given how quickly it appears that the US has disintegrated as a defence partner, but it all seems way more reasonable when you realize that just this bit of it is ~9 years in the making even though it only took 2 months to finish the job.