TDG - 2000.02
All responses were fairly similar in this instance so there is not that much room for discussion.
Firstly a number of the responses advocated the use of pepper spray to subdue either the woman or both of them. This is probably a valid response but I would prefer to not use it especially on a small, injured, drunk woman. My preferred option is to not let her out of the car in the first place until I can concentrate on her fully.
This is always going to be a difficult situation and I don't believe that under the given circumstances there was much physical danger to you. He was not violent and the punch was probably a reflex action as you put your hand on his shoulder, she is not threatening with the bottle and possibly doesn't even know it is in her hand.
But you would have to be prepared for aggression, the last thing you want is to get into a struggle with two inebriated people. But remember you are in a public place, any overt violence on your part toward the woman could be seen by a passing motorist and land you in hot water.
I believe that if you let go of him and made distance, they would both calm down and probably ignore you as they consoled each other, you could leave them to it. It's a difficult call to make you would have to trust your instincts.
That's one of the benefits to thinking about the situation like this, you can try a number of options out and if you ever do get into the situation you have a range rather than one set response.
It would be easy to adapt this scenario to fit your needs, say if you are a club doorman, and get the full benefit, just remember these main points:
Don't get caught up in the circumstances of the scenario, you have no control over why you are there, react accordingly.
Don't think too hard, but be sure you do cover all eventualities.
Give as much detail as possible, explain you actions and the rationale behind them.
Most importantly, see it as a learning experience, look at all responses and if you like someone else's better that yours, study it and incorporate their techniques into your own training, who knows you may have to face the situation for real one day.