A friend of mine asked me this after seeing Whiplash (2014) last night, and I was not quite happy with my own answer, so I'll throw it out there to see if someone can up with somthing more conclusive:
The movie is about a young drummer (Andrew) who tries to achieve greatness and a teacher who pushes his students to the limit with questionable methods.
The main plot revolves around Andrew trying really hard to make it in Fletcher's band and the relationship between him and Fletcher. However there is a sidestory about Andrew and his interest in the girl that works at the cinema, who he dates at first but then drops again after struggling with his spot in the band.
What is the point of the girlfriend plot line? It seems rather unrelated to most of the main plot and is handled too shortly to be of much relevance on its own. (e.g. as an additional love story element in the movie)
Why were those scenes put in there?
My interpretation was that this is supposed to show Andrew's determination, that this was set up so that he can break up with her for the music, showing that at this point he is willing to do everything it takes. Is there more to it? And what does it mean that he is trying to reconnect with the girl in the end?