Now that I've thought about things for a bit (hey, I'm an editor, it's what I do), I think I have a better idea of what's going on.
Overall, this group of characters is generally quite self-aware of their own flaws. That doesn't mean they have control over their reactions to a situation, just that when they get some time to think things over, they're usually willing to admit what they've done wrong, and even apologize when necessary. Even with the rough handling they toss at each other, there's usually a line they try not to cross.
In this case, I think Dora was expecting Marten to do his usual guilt trip confession so she could rib him about getting hit on, and when he didn't come through, the surprise coupled with the insecurities triggered this reaction. Afterward, she'll likely feel bad and try to make it up to him.
I think my main question is whether Marten will come back with a little bit of spine, which he has every right to do, or whether he'll meekly accept this and maybe even let it fester.
Meanwhile, if things don't quickly blow over, Faye will be seeing cracks in the Marten/Dora relationship, which will complicate her own feelings. I don't know if any of this is what Jeph has planned now that it's happening, but it's very possible that all this is something unexpected building out of what seemed a harmless joke (which often happens in real life too).
Or it all is just a one-off joke and something completely different will happen on Monday. While I like to analyze stories and characters to death (that editor thing again), I also am perfectly willing to enjoy the ride the author is taking me on. When I really want to control where a story zigs or zags, I write my own.