How to make my girlfriend more interested?

So my girlfriend of several years has recently decided she wants more "freedom", which basically involves going out to bars until all hours of the night. She is confused and admits it. However, I know she has not cheated at this point and loves me, but she is being more rude around the time she is going out to me, like she is trying to distance herself. The rest of the time she is great. My question is, from a psychological standpoint, how can I make her respectful/interested? The only thing that works is making myself unavailable or calling her on her bitchiness. Please good advice everyone, I don't need to break up with her yet, but if the time comes I will.