Maybe you've never been snapped by a towel by someone with intent to harm you, but I assure you it can leave quite a mark. I have 3 older brothers.
Ingrid bolted to her brother's house where her SIL took the photo of her face.
From The Guardian article:
“Ingrid’s explanation is significantly strengthened by other evidence,” the court said. “She left the house and moved out. The defendant, in turn, sent her a message the next day in which he strongly regretted the incident, emphasizing that he needed help and that he wanted to see a doctor and psychologist.
“The court therefore assumes as proven beyond reasonable doubt that the defendant hit Ingrid in the face with a blow with a small and damp towel.”