In the section titled The Plague, what is something Summer has not been happy about this year?

From the text:

One of the things I’m not loving about this year is how a lot of the kids are acting like they’re too grown-up to play things anymore. All they want to do is “hang out” and “talk” at recess. And all they talk about now is who likes who and who is cute and isn’t cute. August doesn’t bother about that stuff. He likes to play Four Square at recess, which I love to play, too.