Some friends were visiting from another country. Last night there was a mix up about the arrangements and I went out of the restaurant to meet my friend and her daughter - a 19 year old uni student . They were arguing on the pavement and as we entered the venue With me walking ahead of them I glimpsed my friend slap her daughter really hard across the face - I continued inside and eventually my friend arrived without her daughter who had returned to the hotel. She mentioned the slap but said her daughter had called her a name and pinched her hard to which she retaliated. I said it was not a good situation but took the cowards way out and didn’t tell her how shocking it was. We continued the evening. I feel badly for not intervening WWUD?