Beck is your girlfriend, you don't actually love and care about her that much. You only use her for her body, that's all. And, you only came back home at night. Once she was asking you why you were home late, you only make excuses and uses your manipulation skills on her.

When Beck finally discovered your only using and manipulating her. She immediately confronted you "You made me look so naïve.." she said in a low but stern voice.