I have mostly stood up for myself. The public isn't very helpful. Sometimes, even friends (men/boys) choose to look the other way.
People shouldn't get away with doing this kind of nonsense.
A guy on a cycle grabbed a girl while she was out walking with her mum, I chased him but he got away.
how should the public react?
They should come forward and DO SOMETHING in whatever little way they can. Anything but they shouldnt just stand and watch. That makes them equally guilty by not doing anything.