When Emma was done using the washroom she came out to the hall to find any empty classroom she could read in, not having any boyfriend to cater for could make you serious.
She would've respectly chosen to read at the library but as the new rules implies, the library was off limits for now. Several empty classrooms but only one caught her eyes, from the transparent door she watched Flynn and Ivy laughing at something only they know about.
Flynn tickled Ivy and she laughed again, they aren't aware of Emma's presence, so they continued doing what they were doing like no one was watching.
What Emma didn't understand was that Ivy was the main cause of their relationship breaking up, but that didn't bother Flynn, he still kept his close relationship with her, while she suffers emotionally from this.