[saiwong]

It look like Ryan was just play-fighting Roxy. However, maybe Ryan didn't know his own strength and punched Roxy harder than he intended.

Roxy checked the area were he punched her, so maybe saw bruises.


All speculation part:
Roxy's talks in the diary room and not wanting to be around Ryan is difficult to understand. Maybe the punches awakened memories of the past. Maybe she was punched sometime in the past (domestic violence) and this incident provided a flood on memories and a reminder about this past incident and caused her to react this way.