Dortmund don't have good form in Bundesliga and even they won against PSV in Champions League, it won't improve their form in Bundesliga shortly. They even return to Bundesliga with many tired players and probably they will have a tough challenge by playing against Frankfurt. Frankfurt are not weak and Dortmund will have to play against Frankfurt with many tired players.
Dortmund will not easily to lose but they will hardly to get three points from Frankfurt. I think this match will end with one point for each team.
Dortmund still has good strength this season but they are not able to maintain consistent performance, that is their problem this season but currently Dortmund have much higher motivation to finish in the top 4 so I think they still have a good chance big to win the match against Frankfurt especially since Dortmund will be playing at home.