It's actually more stupid for her to stay with kagerou because he can't see anything with her there. He won't even listen to what she has to say. Let him be depressed and thinka bout what he's done.
but wont it make kagerou hates human more? and since it will change his way of seing saving the world a bit moving toward ending the world?
mah lets just wait for the scene brings it end ╮(￣▽￣)╭
Honestly. The way he was talking. "Humans ...are bad" and shit. Shows he's thinking of them as Us Vs Them and not as the same people. Because Momiji doesn't view them like that and still retains that part of her humanity she decided to leave him. It's not even because the humans that she left and if he can't see that then he deserves to be left behind cause there is so much more for mojiji. Ok sorry I went on a tangent
but i think momoji got her humanity back since kangerou kiss her right and some off her kii or such was taken by kagerou.... and i kinda think like kagerou only receiving the old momiji way of thinking. such as in the first stage of momiji changes, she value everyone that pick on kagerou is her enemy and needs to be kill. and now that side has been in kagerou.... hemmm
momiji was so stupid i think? like she wayyy to depressed about things going on and like what the heck just leavin like that and yups she's got eaten...