First, fuck Russia.
That said, this is nearly a non-event from the US/EU perspective. Ukraine is not part of NATO nor any other major collective defense agreement. Under almost no circumstances will Europe accept the risk of a wider war with Russia, and the US is not really any more willing. The west will continue to provide weapons, advisors, and sternly worded letters and threats of additional sanctions to Moscow, but that’s it.
As for Russia, it has neither the conventional combat power to decisively defeat Ukraine, whose armed forces has steadily albeit slowly improved in quality since the conflict began, nor does it particularly want to. Russia is mostly fine with the conflict being “frozen”. I’m not saying they won’t potentially begin a new offensive to take some additional land, but we’re not talking a blitzkrieg across the country here.