You must mean the coups by which Russia seized Crimea and Donbas. The Ukrainian government was not installed by a coup but elected by the Ukrainian people.
You refuse to grasp that part of Ukraine was both culturally and ethnically Russian.
We have been over this many times. The only Ukrainian oblast that has a Russian ethnic majority is Crimea. Luhansk (60%), Donetsk (60%), Kherson (80%), and Zaporizhzhia (80%) have majority Ukrainian populations, but you do not want to accept this.
I just proved the majority there voted Yanukovych, who was driven out of office illegally.
Even if the majority there isn't ethnically Russian, the majority is culturally Russian. They overall speak the Russian language and pro-Russian.
All those parts of Ukraine identify more with their country of original origin.
So, you're actually siding with the Soviets by advocating 1991 borders.