Dora's being overly paranoid I think. I can understand the logic. Faye admits to having feeling for Martin, Martin admits to still having feelings for Faye, the two things standing in the way of them was Fayes inability to be in a relationship, and her.
Faye just had sex, which, despite the fact that she's freaking the fuck out about it, (thought it seems to be less about having the sex and more about who it was with) throws that first hurdle out the fucking window, or at the very least, nudges it closer to said open window.
Dora probably feels like she isn't a good enough reason to keep Faye and Martin from finally hooking up. Her being as insecure as she is, she's going to take it personally, even though, really, This has nothing to do with her at the moment, and she'll probably realize that after thinking about it, or having Penelope talk to her (btw, Pen eating Popcorn while Faye is getting screamed at is priceless, and if were real, I would hug her)
Though I do hope Faye and Martin hook up. Even though I understand where Dora is coming from, I'm still finding the whole reaction annoying, and her blowing up at Martin over little shit is starting to grind mah gears.