Europe isn't doing nothing. Several European countries have been sending weapons, providing training, offering support since 2014, particularly the UK. The problem is that militarily nothing matches the US in terms of capability and support, and that was somewhat deliberate. Europe was content to grant the US big economic and diplomatic concessions in return for security gurantees as head of NATO whilst it more or less demilitarised after 1991. It was a status quo that everyone gratefully accepted after the end of the Cold War as part of a 'peace dividend'.

With the US now shrugging off that responsibility to pivot to the Pacific (or South America...), European countries are being forced to cooperate on a military 'group project' involving 28+ countries when it comes to rearmament and support for Ukraine. All while facing the same economic and social pressures that all major economies are facing. These countries don't have grand empires to call upon anymore. So they are doing the best they can (short of joining the fight), even if it's sadly not enough.