I've long thought... but specifically after Putin invaded and took Crimea...
That the solution to Ukraine's/ Russia's/ and NATO's "Ukraine Problem" is for Ukraine to declare Permanent Neutrality.
Putin would immediately (or close to it): celebrate, offer to double the transit-gas through Ukraine, back out of the Donbass, would never give up Crimea however would offer free port visitation/ usage to Ukraine's Navy or Coast Guard in exchange for energy & other supplies to Crimea... Russia would gain: their desire for a "buffer zone" between NATO and Russia, or, from their perspective, a non-threatening neighbor.
Ukraine would gain: An immediate back off from Putin, a permanent (or as close to it as one can get) reduction in Russian hostilities against Ukraine, their manufacturing region back (intensively located in Lugansk & Donetsk provinces or... the Donbass), other benefits from Russia (as noted above).
Ukraine also could still: arm themselves to the teeth (with conventional weapons) with anti-tank and drone weaponry (anti-Russian materials mostly) while still maintaining neutrality, work with NATO forces in joint "project" work that is non-threatening to Russia, work intensively with the European Union economically, etc...
NATO promised Ukraine they could "one day" join NATO. They would gain with Ukraine's Permanent Neutrality status... a face-saving way out of that, and a "silent partner" as they would still work with Ukraine, maybe even extensively... just without the Article 5.
Ukraine loses the Article 5 commitment. But I think Neutrality gains them far more then joining NATO does... just my 2 cents.
Good article on current tensions:
https://www.yahoo.com/news/nato-says-yes-ukraine-no-130900960.html