I guess I'm not following. How could Ukraine "might have reasonably prevented" Russia from seizing Crimea? How could it have "reasonably prevented" Russia from invading in 2022? Lie on its back with its legs in the air and 'think of England'?
If it is "victim blaming/shaming" that Russia is 100% the aggressor here, then do you feel Russia is somehow a victim in all of this?
The answer to this is political and uncomfortable. The Ukrainian Govt was pro-Russian until it wasn't (see colour revolution). The political pivot away from the Russian sphere of influence was untenable to Moscow, hence the various stages of escalation of this conflict, going back to pre-2014, arguably 1991 when the USSR collapsed.
IMO, this is a civil war, colonial conflict and war of aggression all rolled up in to one big mess. One side believed they had the right to self-determination and the other side disagreed with that.
It's a civil war because Ukraine is not a united polity and there are groups of people in the Country who support Russia.
It's a colonial conflict because Ukraine is a colonial interest that Russia considers in their sphere of influence:
It's a war of aggression because Russia felt threatened enough that it had to act. The tanks rolled out of necessity in Moscow's eyes.
"How might Ukraine have reasonably prevented this?" is kind of a pointless question because if it were possible, it would have happened. Both sides hold views and positions that were/are untenable to the other. Might is right and the conflict will reach its conclusion, one way or another.
The real question is "how does this conflict conclude and what is the outcome of that conclusion?"