What is even going on with these two? I'm so confused with what the author intends to do.
This chapter Makio states her fear that it would be unfair if she allows herself to be closer with Asa . Kasamachi points out that a) she is already closer than she wants to admit so that is like...why are you trying to be distant, Makio, it is kinda too late for that, no? Isn't the real fear here that you will fail her if you took your relationship with her more serious? b) that she too has been treating their past relationship between them the same way. (And maybe still is considering the first page).
Makio then realizes three things: a) Kasamachi has been aware she never thought of herself in a relationship with him and b) and that this too might have been motivated by a similiar fear inhibiting her from being emotionally close with Asa and c) that this was one of the reasons for the strain on their earlier relationship.
Now here is some speculation and interpretation on my part: She sees herself as incapable of properly connecting with people and thus unsafe.
"I feel like I've always had to be rootless plant."
But she now wonders if that was just the fear talking and limiting her. And thus she considers of also opening herself for Asa and trying to be more emotionally expressive.
Which has also the baggage of being the daughter of her sister: someone she held long in contempt for following unthinkingly society's norms but Makio during this story has come to realize her sister was more complex and was also struggling but still bravely raised a kid showing that in some ways her sister has gone where Makio shrunk from. Not particularily in getting kids or becoming married, but daring to be deeply, inextricably tied to people, even if the marriage seemed to not have worked out.
And thus the guilt, fear and uncertainty Makio is feeling in the last pages. She is considering a leap that fills her with fear and challenges her ego (how she perceives herself) and she is unsure if such a socially incapable person as her deserves getting close to the kid her sister raised.