On the other side - Ukraine (however I wish differently) would have an EXCEPTIONALLY hard fight if they intend to take-on russia, and even if I would support them wholeheartedly - its up to them to decide what they want/need more: hard fight ahead, 2 ruined regions with lots of strings attached or a real hope (some maybe would say SEMI-real) for true independence from russia.
Ukraine taking on Russia is not even possible scenario imo. They are barely managing their own civil war with Russia's few thousands extra mercenaries/soldiers (own NATO estimates).
With current balance of power they could not blitzkrieg deeper than 10km into Russia before being completely destroyed by the massed Russian presence at the Ukraine-Russia border, and then Georgia scenario would happen again and they would have a legitimate reason to directly intervene and occupy all border regions and seek very beneficial terms.
Russia has very good defensive position, unlimited access to rebel controled territory and overwhelming forces.
Without external help I dont see anyone from Kiev govermnent ordering direct confrontation... except if they intended to sacrifice themselves to create a media scandal, like when they ordered the garrisoned Ukrainian soldiers in recently annexed Crimea to not surrender at all cost, which didnt work at all.
The "worst" they could do is continue the war while being slowly expanded upon by the rebels, until NATO/EU/US think its time we stop the east threat getting closer to their own border and find some casus belli to throw at them.
The problem is, like with the Crimea situation, national morale is hardly controllable, the country may just stop fighting after a time whatever the orders if the organisation/supply/morale drop too low.
The reports of surrenders in Ukraine shows that it already happened several times locally.
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