That bit wherever she said 'Don't go'? I suspect the cause of that will also have something to do with why she didn't believe Kozuka's confession. Hopefully we'll get to learn a bit more about that
I imagine she suspects that Kozuka's efforts to make more money are an attempt to get out of their arrangement. Which they are, but not for the reason she thinks. She thinks Kozuka wants to be free of her, Kozuka actually wants the arrangement to get out of the way of their relationship.
we are approaching dangerous levels of mommy roleplay
wait... when she looked at that mom with her kid, was she jealous of the kid?
edit: also this chapter needs an insane amounts of head pats
tag.
We don't know her home life or background, so it's possible, but it's also possible that she was thinking about the whole lesbians/children thing. There are a lot of barriers to same-sex parenting in Japan, and wanting children is often a reason past relationships have failed in yuri manga stories. It's a common fear among gay people, especially people who have feelings for someone that is straight or bi, that they'll eventually want to move on to a relationship that can lead to children.