Focusing on the Champions League too much and having problems in the Bundesliga on one hand isn't very ideal for Dortmund at all. Dortmund's main target must always be to finish the season in top 4 at worst. Because the Champions League is like a tradition for Dortmund as they can normally finish the season in this area easily.
But right now things are going really badly for them about this topic. While Stuttgart and Leipzig are performing much better Dortmund will need to work much harder than this. As there is a long time to go for next round games in the Champions League Dortmund had better work on their weaknesses in the Bundesliga.
Borussia Dortmund is currently six points behind Leipzig and that is quite a lot so Dortmund will face quite a lot of difficulty in catching up, especially as the two teams above them can be said to be performing quite consistently compared to them so there is a big chance that we will see Dortmund only playing in the European leagues except for Leipzig and Stuttgart in the middle of the season experienced problems in maintaining their performance and Dortmund managed to make the improvements needed because their front line and their defense line were quite bad this season, of the top six teams in the standings they conceded the most.
After the New Year holiday, Dortmund will face three weak teams, they should be able to get 9 points to continue to maintain their chances of returning to the top four and securing a Champions League ticket.