Putin is invoking the
prisoners' dilemma in order to enforce a militaristic stalemate.
I also think that people here are wholly unaware of how popular Putin really is, especially in the Donbas region. Not everything is propaganda, Putin is
genuinely liked by many eastern Europeans. The reasons for this are multiple and probably as irrational as Trump's popularity in the US.
One key factor is that Russia has been sending a lot of financial and economical support to its eastern neighbors. In contrast, the EU has done very little for the prosperity of many eastern countries, oftentimes sanctioning them when they didn't satisfy the conditions for membership or keeping them on the waiting list for far too long.
Believe it or not, but many Crimeans are actually
happy with the annexation most notably because of the 20 billion dollars that Russia invested in the region:
Also people underestimate how
insanely important Kiev is for Russian people, so it is no wonder that Putin is finding a lot of support among his own population and military:
If you truly want to understand this conflict, you need to understand how Putin is viewed from a East-European perspective, where the EU is largely fallen into disfavor and Russia is sending a lot of support to the ex-members of the now defunct Warsaw pact.