As an American, I have plenty of disappointment in government right now with my own. But it's also incredibly disappointing how many other world leaders are letting Trump roll over them.
The trade wars go both ways. Certainly it can be a bit of a collective action problem when it comes to individual countries that are smaller than the US, but the EU as a whole should be able to negotiate on even-enough footing with the US on these kinds of issues.
The thing is, nobody else wants trade wars. Both sides of a trade war lose in a system of otherwise free commerce, the "winning" party is the party that is willing to sacrifice the most to make a point. Everyone but maybe the super wealthy are worse off. Americans are paying the price for their government's idiotic tariff game, but the real cost will come over the following years, and in some cases decades.
The EU is trying to minimize the damage for its constituents, they're not interested in a stupid power play. Threats of reciprocating in trade wars are meaningless if the leadership you're threatening doesn't care if their people starve.
Playing tough doesn't matter anyway, the American voting public will just blame the EU for all the bad things that happen if the EU's actions do have an impact, laugh at the EU if a diplomatic solution is found, and the American leadership will repeat whatever the last guy to verbally jerk off Trump said for at least the coming three years.
In a way, it's kind of impressive. The EU was not ready for America to devolve into this level of clown politics this fast, and that left them unprepared.
Any war goes both ways, but that's not the point. The point is: can you win a war against your adversary? Can the UK win a trade war against the US for example?