So to start off with you need to understand that nato is not a defensive organization from the bombing of Yugoslavia to Libya nato has always existed as an offensive alliance. The USSR requested to join nato in the 1950s and then Russia did again in the late 90s. Both were rejected because nato is built to combat Russia not to protect europe.
When they broke away from the USSR Ukraine's constitution enshrined their neutrality. The only reason to renounce neutrality is because you are choosing confrontation. In the decades leading up to the war ukraine removed their neutral status from their constitution and decided they were going to join nato (more so that nato decided they were going to pull ukraine in. The majority of Ukrainians was well disposed to Russia even after the coup)
BBC has several reports from just after the miadan coup in ukraine talking about the fact that the "far right" (passive voice for nazis) had taken over the government. There's also all the stuff about them honoring Stephan Bandera who was a ukrainian nazi wannabe.
Then after the coup the first things they did were to remove language rights for Russian speaking Ukrainians so they couldn't use their mother tongue in school or legal documents or in court, etc. essentialy making them second class citizens. When they protested that they got murdered most notably in the Odesa trade union burning.
So instead of being subjugated by fascist racists the majority Russian speaking areas decided to break away. There was a civil war between the break away states and the keiv government for 9 years with 2 peace negotiations (the Minsk agreements) that were completely ignored by keiv and that time was spent building up Ukraine's military. So then in 2022 russia said "common guys ukraine isn't doing what they promised" and Ukraine started massing troops on the borders of the Donbas and increasing shelling, so Russia started massing troops on the border and saying "we need to talk about this or we are gonna get involved directly" and the other guarantor states (germany and france) said nothing. So then Russia started its SMO.











