It's interesting that we have no popular qualms about the Monroe Doctrine, which we've abused to interfere with and overthrow legitimate governments in South America for decades, but when Russia takes a Monroe-Doctrine-esque position with a country on their border it's out of the question.

I see basically 3 possibilities. Ukraine agrees to neutrality, Ukraine resists neutrality and has its country destroyed and is eventually forced to agree to it anyway (what is happening now), or the western powers start a hot war with Russia and risk WW3/nuclear holocaust. Given those options I'd go with the first.