The embassy cannot become involved in criminal cases. All they can do is to provide a list of recommended lawyers.
If you go to gaol, then the embassy can support you.
This all happened as they were checking out of the hotel. That was when she realised that she did not have the hotel key. She was paying the bill, the boy went to fetch the key from the nearby shop.
She could not leave Thailand as she was arrested for the assault. The boy left as planned. I believe that she is still in Thailand facing the assault case.