Earlier quoted context omitted.
There have been literally (not figuratively literally, literally literally) zero diplomatic resolutions of military conflicts or tensions with Russia during the Putin era. None. The closest one you can see, if you squint extremely hard, is the detente of 8 years that that followed the invasion of Crimea. And then we know what happened. Conflicts in Putin's Russia end militarily, always (usually in victory or stalemat…
Negotiated peace can be a thing if there is enough of a threat behind it. I imagine Putin would like to be able to nuke Ukraine but the US have threatened bad things if he does. I think if the west had made more of a threat before the 2022 invasion Putin may well have backed off but Biden was like if you only invade a little bit we won't do much which is kind of how it went.
"This hasn't worked for 30 years, but this time it will for sure!" makes for pretty awful geopolitical strategy, historically. But you do you.
(Your broader point that Putin's actions are constrained by nuclear deterrents is obviously correct. But it's very clearly not a point about diplomacy!)