Just wanted to critique this line of your critique,
“She could tell from the particular way he moved around the counter, post-endorphins quiet.” is pretty weak; he’s in running clothes, presumably he generally runs before coffee… it’s going for intimacy/her knowing him well but achieves the opposite in context. I’d cut it.
I don’t think she can see Kai yet. She just woke up. I think she’s still in the bedroom at this point and listening to him move around in the kitchen, so she wouldn’t yet have seen that he’s in his running clothes. I agree that “the particular way he moved around the counter” might suggest she is looking at him in that moment but I took it that she inferred the way he was moving from the sounds he was making and she presumes that he is at the counter because she hears “the sound of Kai making coffee”.
The next line is, “”You’re late,” he said when she appeared.” which, while it’s referring to his perspective, suggests to me that she also didn’t have a line of sight before that point.
I thoroughly enjoyed reading this. Not sure why it isn’t getting more engagement.
If you avoided reading it only because you assumed it would be AI slop you should give it a read.
That being said, it being “pretty good” may not be that much of an endorsement of GPT-5′s writing skills. I expect most of the credit for its quality should go to Trevor the, presumably human, editor.