You can, like you said about the girls, just leave if you don’t like the Ukrainian government’s conduct of the war.
I wish I could. It's very hard. All cities are full of blockposts that check docs of all men, there are conscription officers with police at subway station entraces/exits, at bus/train stations, etc. It's hard to even get out of city, it's hard to travel between cities, and borders is a whole different story. EU borders from Ukrainian side are patrolled with night-vision drones, photo-trap cameras, even some helicopters. It takes extraordinary skills and luck to cross the border. And regarding Crimea, can you open the map and tell me how I'm supposed to travel there from Ukraine even if there were no blockposts? I mean, it requires crossing the battlefields. Those who are in Crimea though, they can leave through Russia and go wherever the fuck they want, even go back into Ukraine through basically any intermediate country after leaving Russia.
Since it's Kyiv it would mean it's finally over I guess. Russia has open borders so if we eventually end up in Russia we can just leave.