I’m sorry we’re misunderstanding each other. Your argument was that “Koga doesn't value Aya in the same way, and I don't mean like she's in love or not, just does not care enough about her.”
That’s what I’m arguing against—romantic or not, their relationship is not (yet) of a nature where Koga’s failure to tell Aya about the offer to move says anything at all about how much Koga “cares” about or “values” Aya. Certainly they have different attitudes about the subject—one has to make a decision and the other one fears being left behind.
Your original statement (the one I just quoted) absolutely implies that Aya cares more for Koga than Koga does for Aya, an idea that the entire chapter contradicts.
Okay, we can agree to disagree, I think the chapter shows it, that's just how I felt while reading, not making a post-reading analysis, you think it does not. That's it then, debate settled
It's worth mentioning that Koga not telling Aya does not mean that Koga thinks Aya doesn't deserve to know, or that she doesn't want to tell her.
It's very possible, I would say even probable, that she doesn't know what she wants to do.
Kanna said she came to steal Mitsuki away to America. We know, and Mitsuki probably knows, that this is actually an attempt to get back together with Joe, who isn't going to move without Mitsuki. She isn't an idiot, she is probably aware of the fact that her uncle, who she cherishes, gave up the love of his life to give her stability and care, and it has probably occurred to her that if she were to move to the US, her uncle would be happier. That's a pretty good reason to consider going regardless of what's going on with Aya. Mitsuki is also very interested in western music, and probably culture in general. Going to the US probably sounds like a pretty cool opportunity.
But she's also aware of her feelings for Aya and the budding thing that's building up between them. Choosing to stay or go isn't a simple decision, but some part of it has to feel to her like choosing between her own happiness and her uncle's. He knows that, too, which is why he makes a point to tell her that he doesn't regret staying at all. So she doesn't know what to do, so she's doing what she does and stewing about it internally until she makes a decision.