Puniru is becoming less and less dependent on Kotaro's attention, which is good for her because she's growing as a person...and bad for Kotaro, who is afraid of her abandoning him because he appreciates her, even if he won't say it outright.
"The change of seasons is the end of a connection"
This sounds oddly prophetic since the last episode of Season 1 of the anime has Puniru acting like she stopped being friends with Kotaro, despite there being nothing of that in the manga. Did they do it on purpose to gaurantee viewer engagement?