In order for there to be a "too", I would have to be doing straw man argument myself. And I'm not. My reasons are valid, yours isn't.
I don't necessarily have any problem with the position you are advocating, but if you want to be taken seriously, you really will have to open yourself up to considering other people's points of view, rather than simply dismissing them as stupid or invalid without any further consideration. Deliberate misrepresentation of people's views, such as "Yes yes, we get it. Dora can never do wrong in your eyes," will not do you any favors. You should address their arguments, rather than jump to conclusions about what is behind them.
No-one is perfect, and that applies double in the QC world. Everyone in this comic has their troubles, and I can assure that pretty much everyone here would be aware of that. That includes Dora and Sven both.
I am not so sure that I would apply the word 'toxic' to Sven, it seems a little strong. But I can see why Dora might. Obviously their relationship is somewhat toxic, as I mentioned earlier, and neither is entirely blameless. Apportion blame as you will. Also, whether distancing herself from him is the right move, I don't know. Maybe it is, at least for the time being. As someone else said, it's probably a better option than her bludgeoning him with a baseball bat.
FWIW, I don't hate Sven, but he has a few lessons to learn.
Edit: I forgot to mention that there are a couple of things I do disagree with. I don't think that "breaking Jim's heart" (whether she really did or not) makes Dora a terrible person. A first date does not oblige anyone to follow up with a relationship. Also, there was a throw-away line along the lines of "Marten is now forever alone." Really? A little dramatic, don't you think? Marten will find someone else, in his own time. If he doesn't, that's not Dora's fault.