Luftstalag is right. It's no secret Bayern is the club many Germans love to hate, has nothing to do with BVB. If you're any familiar with German football, you'd know that whole idea of BVB - Bayern rivalry is made up by those who only started following the Bundesliga recently, after Dortmund got into their winning cycle. It's basically Bayern against the rest. That's partly because no other team manages to be a long-term serious contender for Bayern. They have a go at them every once in a while, but mostly, that doesn't last for more than a couple of seasons. So "Schadenfreude" about Bayern losing comes from everywhere, not just Dortmund. (Having said that, it could of course be that Dortmund is currently on the verge of becoming a long-term big club, but that remains to be seen. Certainly hoping for it).
And the true archrivals of Dortmund are Schalke, not Bayern.
Don't know who's said that but I for one would like Dortmund to qualify from the groups. It's good for German football to have as many teams as possible at the elimination phase, and it's a breath of fresh air for another German team to be challenging.
That's the spirit. (Although I doubt that feeling is reciprocated...)