I honestly can't think of a polite way to phrase how bored I am by this point, actually.
Quick question. How many of your relationships have ended with these keyphrases being used? "Fuck you!" "I hope I never see your face again!" or the classic sentence thats made up entirely of swearwords.
None whatsoever (high school "relationships" don't count), at least on my part--I've got breaking up down to an art as far as it being a very simple "This isn't working for ______ reasons", giving them a hug or whatever if they handle it well/agree (most of the time the breakup is completely mutual) and we part ways.
The few where they acted that way toward me, though, I'd interrupt and say "Look, if you're not capable of talking to me like an adult, I'm not going to sit here and let you just rail at me like I'm a piece of shit. I'm better than that and I thought you were, too.", then I leave.
Life is just far too short to waste a single minute of it on people that don't give me the same level of respect and honesty I'm going to give them in a relationship (plus I'm too old to put up with bullshit drama or games in a relationship anymore).
Just because the relationship ends doesn't mean you can't be friends. There was obviously something about a person that someone liked enough to go out with them, if they broke up in amicable circumstances that something shouldn't have changed. The only times I can think of where a person really wouldn't speak to someone ever again after a break up is if they move away, if they stole from them...repeatedly, or if the relationship was really that toxic. Otherwise, whats the point of ever getting to know someone?
Just because the breakup was amicable doesn't mean you have to try to be friends, either, though. Most of mine have been with people I meet in/around the Atlanta area, though, so there is no shortage of people to form new relationships with (I could see this being a problem in really rural communities, maybe, but not a bustling city).
Even in the context of QC, I can't see it being rural enough to be a problem for either Marten or Dora unless they make it a problem. Not saying they can't be civil if they see each other in public, but at the same time they don't have to be buddy-buddy best friends again, either.