When Natsuko said "this isn't love, not even really affection" it seems like it applies to herself most of all. Wanting to hurt someone and make them feel miserable just because you find it fun certainly is not love, even if you are fixated on them and protective of them when other people say things. Trying to push that "you don't even like me, really" thing off on the other girl just comes off as an attempt to make excuses for herself. "I'm not really doing anything bad, she doesn't even like me anyway, she's just doing emotions wrong. See? She says I'm really important to her, that obviously means I'm not important to her at all. Not my fault she's so easy to hurt."
The second chapter felt pretty superfluous, anyway. As others have already said, nothing changes or progresses, and there's no extra insight or context gained by switching perspectives. It's just more of the same. I guess it's okay if you like watching girls being mean for no reason, but it's not much of a story.