This has me convinced that the degree of western support relies heavily on how well your own forces are doing, and to always remember that past performance is not indicative of future performance. This post goes into the political problems of this intervention and why it is not going according to Russian ideal:
Point 1:
On day 1-3, western public opinion was of no intervention, condemnation, sanctions, but essentially abandonment of Ukraine because of Russian quick gains, gaining air superiority, and destruction of Ukrainian supply lines with long range standoff fire. Russia was making unprecedented (literally, without historical precedent) gains.
After day 3, Russians are getting bogged down by surprising Ukrainian resistance, air superiority was not converted into air supremacy, they are failing to control the narrative, and they made mistakes. Yes, Russians are holding back (more on that in point 2) but that only represents a political mistake rather than a purely military mistake. This emboldened foreign adversaries of Russia which decided to do weapons sales, sending 'volunteers' and even talk of direct intervention.
The problem with Russia is that they're on a ticking clock due to foreign intervention. They have a dilemma: do they carpet bomb/shell for a few weeks to soften the enemy, or do they risk heavy casualties, a PR failure and foreign intervention?
This reminds me of when KMT tried doing this in the Battle of Shanghai. They failed because they did not slow down the Imperial Japanese Army sufficiently, foreigners were uninterested and thus KMT simply wasted their German equipped divisions. Same is true for KMT resistance against CPC. There was little pro-KMT intervention because despite all their intervention they were still doomed, foreigners lost interest, and that was their end.
Point 2:
Russia got too arrogant by its previous successes in Georgia, Syria and Ukraine. They thought a little carpet bombing, some PGM strikes and wiping out encircled units with tanks, combined with propaganda, is enough to get the rest to surrender on contact. This is a good strategy against confused, divided enemies to reduce the cost of military adventure. However, they did not consider what Ukraine has been doing since 2014.
Since 2014, Ukraine has been getting more and more radicalized. Unfortunately, by taking Crimea and splitting Donetsk and Luhansk, Russia actually lost popular support from the rest of Ukraine by taking away mobile Russian speaking minorities. So Ukraine lost territory, but they gained political advantage by now demographically consolidating around the pro-west Ukrainian speaking right. It also gave Russia a false sense of security by making them think they had enough popular support to disintegrate opposition on contact. Actually, they themselves got rid of all the weak units that would disintegrate on contact... and left only the hardened ones.
The other part is, they are unable to defend their narrative and are still allowing enemy points of view to shape the discussion. They have neither been able to promote their own point of view or silence the enemy point of view. This is a total loss on the information front which again, results in problems from point 1: going from tepid opposition and condemnation to active resistance.
Lessons for the future:
1. Winning or losing is snowballing. If you win hard, it keeps foreign opinion down and shuts up opposition. But if you start losing even a little, you will soon find foreign weapons, insurgents or even a no fly zone near you.
2. Do not assume adversaries are going to surrender upon attaining mere air superiority and a little carpet bombing. Only air supremacy and total devastation will do. This is going to result in bad PR but...
3. Media control is absolutely vital. If your side has no hope of shaping the narrative then don't even try to, just go for it. Holding back means failure because they sure won't hold back and you'll be demonized just the same.
4. Prior success could harden enemy resolve which is important when considering foreign intervention. Russian past successes set them up for bigger obstacles today.
5. Never underestimate nationalism. Do not assume that a democracy is actually a democracy, it could simply be a fascist state in disguise, and while fascist states often fail over the long run, they can still deal significant damage before going down.