<human>: Give me the gist of the text in a nutshell

Background - my girlfriend and I have been good friends for years and in a relationship for the past 2 years. We have done fairly well and I have learned from other people that communication can make or break a relationship. I have communicated to her that I don't feel like she cares about me. For example, every night I make sure to listen to her day, tell her I love her, try to help her with her problems (when she asks) and overall just try to be there for her and keep her happy. However, if I say something that is unintentionally offensive or hurtful, she refuses to tell me what it is that I said and gives me a cold shoulder until the next day. Really all I can do is wait until she isnt mad.
The real problem is that we both are pursuing high standard careers and participate/lead multiple clubs and activities together. If something were to happen between us, the clubs would not function and our resumes would both suffer.
I have told her how I feel about her acting this way and she says she will change and cares about me but then proceeds to do the same thing the next day. I would really appreciate some advice on what to do next.
<bot>: feel unloved by girlfriend. Says she will change but she hasn't. Tried communication. Breaking up is a bad option, but if things get bad enough I guess may become necessary. Next step?