Caveat first. This is just a hypothetical scenario, and not legal advice. I am not an attorney, not did I spend the night at a Holiday Inn Express last night.
You and wife are sitting in the car, such as stuck in traffic. Then random_person_001 walks up and throws a rock thru the passenger side window where your wife is sitting, (you do have to remember that this all goes through the reasonable person perspective and that reasonable man is based on you). Also what happens next is important. If he reaches into the car, he is the aggressor. But if he starts to run then you chase him down. You are the aggressor.
That’s why training both mental and physical are so important. To be a responsible firearm owner you have to be able to process these things.