I am indeed certain they're frustrated. And equally frustrated by the opposite snide remark that the US is "willing to fight to the last Ukrainian". The US is damned if it does and damned if it doesn't.
There's a surreal agreement that somehow this war can be contained as long as we obey certain arbitrary rules. The US can send all the weapons it wants (except nuclear ones), but they can't send soldiers. The fight is against the Russian army, not the Russian people -- except for the fact that they (supposedly) just re-elected Putin. If Putin starts to feel the war will damage himself, then he'll feel free to end the entire world.
This is bizarre and insane. But not necessarily wrong.