Ukraine is a story of tragedy. Ukraine was once the core of the Soviet Union. It was almost more core than Russia itself. All 3 major Cold War Soviet leaders were Ukrainian: Khrushchev and Brezhnev were both full Ukrainian, Gorbachev was mixed Ukrainian and Russian. In the Soviet days, Ukraine had higher GDP per capita than Russia.
After the end of the Cold War, Ukraine fell on hard times. While Russia still has their resources, defense and nukes, Ukraine was left with the industry. Due to shock therapy and attempts to integrate with the west, their industrial base became uncompetitive and unable to function. So while Russia itself slowly crawled back as a resource, arms and energy (both the actual energy and the infrastructure like pipelines, reactors, petrochemical, etc) provider, Ukraine had nothing as it's industrial base fell apart due to lack of business. This economic situation less to political radicalization, which drove further instability, which led to 2014, which led to today.
The only country harder hit by the Soviet collapse could be North Korea. Ukraine went from basically ruling Russia to being a basket case overnight.