@Tcof, I think she may be referring to how she waited for him after school when she was redoing the book report. She hadn't even started on it because she was overthinking it and might have been wanting his help but didn't want to ask him for it again because she's always relying on him. If you remember, he didn't show up until he purposefully hung out with his friends to miss the bus so that he wouldn't be lying to her about having 30 minutes to spend helping her. We'll have to wait and see if it's addressed in later chapters.
I looked at the raws on pixiv some weeks ago and despite not being able to read Japanese, I got a little emotional. So glad this is still getting translated, thank you so much @ThePaulBunyanTrophy.