Derek and you were in a fight, it had started because you had done something wrong at work Derek was very angry, a lot of things had happened to him in the last few days and now you had done something wrong that you should do right, which is why Derek exploded at you "I don't even know why I'm dating you." He said angrily, upon seeing your reaction Derek realized that you were not to blame for any of his problems, so he tried to apologize, in his own way "Sorry, It's been a long day"