Two places at once
Saturday, three o'clock. Nora promised to be in two kitchens. She meant both.

It happened the way it always happens. On Tuesday her grandmother said, "Saturday at three, we're doing the apple cake, I bought the apples," and Nora said yes because she loves the kitchen that smells of butter and because her grandmother had bought the apples. On Thursday her best friend said, "Saturday at three, my place, I need to talk, it's about him," and Nora said yes because her friend's voice did that thing it does before she cries.
By Friday night both yeses were sitting on her chest. She lay in the dark and listed them out loud, the way she does. Grandma. Best friend. Both at three. Both real.
The easy version is a text to one of them. "So sorry, something came up." Something did come up: her own mouth, on Tuesday and on Thursday. Her grandmother would say, "Of course, darling," and bake alone. Her friend would say, "No worries," and mean the opposite.
At ten on Saturday Nora did the thing she hates most, which is to make two phone calls instead of sending two texts. To her grandmother she said, "I promised someone else the same hour and it was my mistake. Can we start at five? I'll do the washing up." To her friend she said, "I'm yours till quarter to five, then I have to go. Is that enough, or should I come tomorrow and stay all afternoon?"
Her grandmother said five was better anyway, the apples needed to rest. Her friend said quarter to five was fine and then talked until half past, and Nora stayed, and got to the cake late, with flour on her from the first kitchen because they had ended up baking at her friend's place too.
Nobody was angry. That is not the point. The point is that "yes" is cheap on Tuesday and expensive on Saturday.
Nora called instead of texting and admitted it was her mistake. Would you have done that, or sent the "something came up" text? What is the difference, really?
Two points of view
She has time. She also notices, every single time, when someone makes her the easier person to cancel.
She needed Nora more than the cake did. But she also knows Nora says yes to everyone, and wonders what her yes is worth.
The story does not end here.
You might have seen it differently. That is part of the point.