Dora just didn't care about her as a friend as much as she thought.
That's a two-way street though. I would remind a friend who tried to pull a 'you obviously didn't care about me as a friend because you fired me' that they put me in the horrible position of having to fire a friend for drinking on the job, and point out that if they truly cared about the friendship then they wouldn't have put me in that awkward position in the first place.
Ah, yes. The infinite finger pointing. It's like a flame war, but less typing.
Friendship is not transactional. People tend to think it is, but only when they need something or have been hurt. Friendship is just a group of people bumbling along in company, trying to make room for one another. Because it feels good.
At some point we invest a part of ourselves in the others. The same way your brain can be tricked into thinking that a fake arm is attached to the body. When they hurt, we hurt.
We expect it to go both ways. In a real friendship it does. But the fact is, the part of our friends that they invest in us will not be the exact same as the part we invest in them. Overlap? Likely. Perfect match? Never. At some point something they do will hurt us or vice versa, We tend to think, because mutualism, that they should have known. In the case of Faye, the argument stands that she should have known. Common sense, after all. But Faye's world had been reduced to looming hurt.
Faye could argue the, "hey! looming hurt!" Dora "should have known." But ultimately, as friendship goes, neither argument is valid. (which introduces the employee employer angle, and Dora is super valid there.) Either they can see past the friendship error, or they can't. That doesn't make a bad friend of either. It doesn't erase the validity of what they used to have.
Of course, they will patch things up. Unless Dora's at the bus station. But I don't see that happening. Not like this. Angus, Gabby, Sara? Sure. they had roles to play and the role is done. Dora is core cast. She might get bussed out--a writer can get sick of any character--but it will be a storyline of it's own. Otherwise, someone might start a movement about ethics in webcomics.