Why does Kate refuse to leave the house then?

David: Hurry up, Kate. We’ll be late.
Kate: I am hurrying. I can’t move any faster.
David: It’s always the same. We can never get anywhere on time.
Kate: Right! I’m ready. Really, David, if you gave me some help around the house, we’d never have to hurry like this. I can’t do everything, you know.
David: Well, we’d better be off. We’re late already.
Kate: Oh, no! It’s absolutely pouring. We can’t go out in that. We’ll be soaked.
David: Nonsense! Come on. It’s only a shower. It won’t last long.
Kate: A shower? That? It’s set in for the night. I’m not going out in that.
David: Well, you’ve got your umbrella, haven’t you? Use that. And anyway, it’s only five minutes to the Johnsons’ house.
Kate: It might just as well be five miles in that rain. And I haven’t got my umbrella. I left it in the office.
David: That wasn’t very clever of you, was it?
Kate: Well, we could use your umbrella, I suppose.
David: We can’t. I left it on the train six weeks ago.
Kate: Oh, really?
David: Well, we can’t stand here all night. We’re late enough as it is. Let’s go.
Kate: I’m not going out in that. And that’s final.
David: I’d better ring for a taxi then.
Kate: Yes. You’d better, hadn’t you?