What To Do? What To Do?

If he was a Security Guard, it would be apparent, by his uniform; so, if he wasn't wearing a uniform, I would consider what he was doing to quite probably not be justified, and would run over to intervene, asking them both what was going on, and making it certain that I wasn't going to stand by and watch him carry on such behaviour. If there was no valid reason given, I'd threaten to call the Police; if there was seemingly a valid reason, but the girl was still not co-operating, I'd tell him to call the Police, instead of attempting to sort the problem out in such a manner. Either way, I like to think I'd stop him from hurting her. It's hard to know how we'd behave, in such hypothetical situations, but I have rushed to help in a similarish situation, in the past. These are situations in which people may be too quick to suppose the man to be at fault, though.

Assuming its not a security guard of course I would help. I'd probably go up and speak to the girl and ask if everything is alright.. then I could judge by the looks on their faces what the appropriate action would be, I'd need to be there to decide what to do.