So, I registered here, as this has probably been the most on-edge-of-seat I've been during the entire QC story (although I started reading late, so I got caught up and read through all the other times that probably would've happened).
I have to say, I'm not for or against them breaking up/staying together. Every relationship has its issues, and as soon as one party stops trying to make it work (by this I mean, resolve problems that exist), it falls apart. On the one hand, by and large, this is true, as I've seen, and in my own experience. At the same time though, it'd be ridiculous to keep taking shit from your significant other. Some things just can't be resolved, and I'd give some examples, but I think you understand my point. I remind myself of this every time myself and my girlfriend fight, and as cold/calculated as it sounds, I keep track of when something comes up again, or when I myself am getting overworkedup about something. Maybe it's just that this is the first comic I've read religiously since I started, but I tend to think Marten does this as well. Not that I'm saying either he's the perfect guy or anything, everyone's got their problems. However, he seems to be a lot more in touch with himself than Dora, who has never really worked on her issues enough to get to that point.
On a side note, if Marten cheats on Dora with Faye before they're officially broken up, I will hate him probably for the rest of the comic. It's a horrible thing to do to a person. Not that that really matters to anyone but me.
Realistically speaking, I see that happening though. QC has kinda been dreamland for everyone for some time, and that would definitely shake it up. My theory?
Dora talks with Sven and becomes determined to solver her trust issues, etc.
Marten and Faye go back to the apartment, finish the Midnight Hobo, and end up kissing on the couch, to which Dora walks in on.
Dora doesn't know what to say, runs back to Sven's, and stays the night there.
Sven goes into "DEFENSIVE BROTHER" mode, goes to pick up Dora's stuff from the apartment, and gets in some sort of fight with Marten (got a feeling it won't be physical though).
Dora Moves in with Sven, and fires Faye.
For some time, Sven and Dora are at odds with Faye and Marten. The rest of the characters try and stay out of it, but side with Marten, causing Dora to come back to Marten (who is ravaged with anger/sorrow at himself for cheating on Dora).
Faye and Marten agree that that night is a mistake (though Faye's real feelings for Marten have deepened).
Faye fakes it with Angus, and Marten/Dora's relationship grows stronger.
Rest assured after all this, no one (viewers or the characters) will forget what happens during the strips that play this out. There will be future strips which reference this with other fights, like Sven getting angry at Dora for going back to Marten, etc.