Ukraine was talking about 3 new offensives that were being prepared for (how harsh or "defensive" those were meant really does not matter, just discussing them destablizes things). On January 15th the legislature approved additional conscription to prepare. After that everything fell apart.
LOGIC: Very predictably, with mistrust already heavy, the rebels decided to take the offensive and not wait (theoretically until Kiev was fully prepared).
All the EVIDENCE so far points to their using this to round out the borders as the borders as they were (with the big whole in the middle and half the City airport under Ukraine control) was not defensible.
Just as everyone claimed last year that they were going for a route to Crimea (and they were wrong), there are no indications that is what they are doing.
Now, the worse things get, again LOGIC and HUMAN NATURE there is a good chance they could eventually say "to hell with it" , and if there is not going to be compromise OF COURSE continuing war will eventually **cause** these predictions to come true.
I used to think it was pretty much only conservatives that thought the best answer to all such things was war, and they have been proven wrong again and again and again. Now it seems that even "liberals" in the US are so brainwashed by years of war thinking some have lost their wisdom too.
By the way: BOTH the US ambassador to NATO and a general in Kiev have admitted in the last few days that while they believe that regular Russian forces are not in East Ukraine. They believe that advisors and strategists may be (kind of like with the US). So maybe finally the tide has turned on that exaggeration.