Hmm. Looks like most of the comments here take the girl as the typical Nagatoro type who actually likes the MC. To be honest, so far I have heartburn reading this, especially since it ends with the girl meeting up with some guy. And yes, typical trope is that the guy is her brother or cousin or something. But I never fail to consider and believe that maybe it's not.
And what if I'm right? What if she has some underlying motive to torture the guy to some degree? Of course, that's just another trope.
I think best direction to take here is to keep the suspense as much as possible. I would hate the fuck out of the story if the author did that, but it'd certainly make me keep coming back as long as there is some form of progress or change. And NO! Don't make it some mystery that needs to be investigated.