Ok. Grandma rocks, possibly literally, but definitely figuratively.
And honestly, not liking anything is a pretty drab and sad existence - only driven by the avoidance of death and pain. If this is meant as an allegory to something, perhaps it's depression? Given the japanese attitude towards mental health, and how depressed people often excel at hiding their struggles, I can see it as more "monstrous" than merely sexuality.
After last chapter, I'm not so sure that she's being honest when she says she doesn't like anything or find anything cute. After all, if she didn't like anything, why would she have come out of the desert and what was that shining light she was walking towards?
I think she had something she cared about, deeply, but then she lost it. The real question is does she realize she's lying and why is she lying? Is she trying to convince her self? Trying to apply a "Monstrous tag" to herself for Itou's sake? To try and drive her off? To appeal to her love of monsters? To try and put some distance between them to make it easier to eat her? I really want to see where this goes.
The artstyle and the topic, obviously, has me going all shadow star and wondering if the monster will eat all (other?) humans in the end and they live together in an empty earth.
It's not yuri, but have you read BIBLIOMANIA?