Daisy had never been this aware of time before.

It wasn’t just that she counted down minutes until the next class, or that she noticed the way the afternoon sunlight slanted differently in September than in August. It was the way her mind seemed to measure days now by moments with Jordan—how long until they saw each other again, how many minutes they’d get before they had to split off in the hallway, how quickly their little pockets of privacy seemed to vanish.

By Monday, their rhythm felt both comfortable and charged with something she couldn’t quite name. They sat together at their library table again, books spread out, the...