In reality, Russia does have a say over its neighboring countries. So do all superpowers.

And yet you have to wonder, on an alternative timeline, what if Ukraine says it won't join NATO and stays under Russia's sphere of influence? It would suck for national pride but maybe under that alternative timeline they won't get invaded now and possibly wouldn't even lose Crimea earlier?

Practically speaking, perhaps you should avoid poking the aggressive neighbor next door, especially when you can't have definitive assurance from the police station three blocks over?

There was little support for joining NATO before Crimea was annexed. Ukraine wanted to join NATO precisely because it realized that it will be devoured piece by piece by its imperialist neighbor unless it does.