It would entail NATO enforcing a no-fly zone, meaning direct combat interventions. So yeah, it wasn't going to happen, at least not yet. I think maybe that Ukraine wants all these things "on the record," so to speak - that they've asked for assistance from various agencies and countries around the world.
I'm not leaving anything off the table here, however. It seems that Putin has gone completely mad, at this point. Next up is Moldova, maybe Georgia. He basically owns Belarus, since their regime is a Putin puppet. As for NATO countries, who knows? If that happens, it's WWIII without question, and the nuclear gloves will come off - especially since his Napoleon-era strategizing isn't working out too well, especially with a mostly ancient motorized army.
What's that they say, that some men just want to watch the world burn? There's no giving him what he wants, there's no appeasing his insane ego.
There is the idea that some Russian general will take one for the team and assassinate Putin, or a mob of them, Caesar-style. Who knows. The Russians are just as brave, and foolhardy, as their Ukrainian brothers, as a rule.