It seems most of you are predicting doom here now, so I feel a need to voice my disagreement.
I happen to have just finished re-reading the whole thing. Yes, starting at number one not too long ago and my browser history tells me I've read more than a thousand strips since yesterday morning (failed exams makes worn-out students pretty dumb, yeah). I don't know if this makes my thoughts on the subject more or less credible, though...
Yes, Dora is worn out in most ways possible and doesn't handle things very good right now. She is mad with Faye, more severe and in a slightly (note only slightly) different way then we've seen before. But we've seen her being this mad with Marten, and she didn't break up with him because of that - not at all. She broke up with him because she was mad with herself, something that at least Faye did notice at the time (but possibly not the readers).
Probably Dora is due for some kind of breakdown, but it's not gonna ruin her, nor her business or her relationship with Faye. Not more than temporary, anyway. Eventually she will be moving forward with her issues and work a lot better than before, you guys need to remember she just started going to therapy. Heck, for all we know, she could even be on some damn medication right now!
I'm quite sure she will be friends with Marten again before strip 2100. Correct me in half a year if I was wrong!