The US military isn't only over there to protect Ukraine. It's also over there to move into eastern Ukraine and extract resources from the territory. It needs a peace deal, to send in the drills. That was precisely what was in Trump's first attempted "peace deal".

If America reneges on Ukraine defense, they break their Trilateral security guarantees, that they and the UK agreed to, in exchange for Ukraine giving up its nukes. That would cause the USA to be seen as a fickle partner, and put all other security guarantees in question (Qatar, Taiwan, etc.)

The USA and Russia companies are in talks to resurrect Nordstream 2 without the EU, and then make billions selling the natural gas to Germany. The USA has promised Russia that it can force the EU to purchase Russian gas by cutting Germany off from American gas. Germany doesn't think that is very funny.

The EU (especially Germany) is completely dependent upon the USA for energy and defense, but America becoming such a terrible ally has them rethinking the wisdom of this.

Now, Trump and Elon scream incoherently at them on Twitter and ramble on racist garbage about Europe no longer being European. Which has them rethinking even harder.