Putin wanted government change and territory annexation, probably most or all of Ukraine (based on his theory and practice that all Russian speaking/formerly Russian speaking and culture-related people are property of Russia). Is there something there for one duly elected govt and sovereign nation (even if they/it are/is corrupt to some extent and struggling economically-) to negotiate over? Hmm.
Truth is neither one of us knows what the negotiations could have been because I don’t speculate what anyone else is really thinking and act like my speculation is fact.
Ii was called for and could have been done. At least it would have been a start.