[throwawaycoder]

It's not always easy to know what kind of relationship people are in. That's probably a reason why people tend to wait until it escalates beyond a certain point.

If people would interfere too soon, feminists wouldn't be happy either. Because that kind of behavior would imply that women are weak and unable to take care of themselves.

[patrickmay]

The average man is five to six inches taller and forty or more pounds heavier than the average woman. Men are also physically stronger pound for pound.

I'd rather take a tongue lashing for being an interfering white knight wannabe than not say something and find out that the woman was too uncomfortable, for all the reasons being discussed in this thread, to extricate herself from the person bothering her.