The holidays are always a tricky time. Honestly -- I'm not sure why Mia did it. She just seemed to get caught up in a wave of some kind of emotion that is hard to quite define. I think perhaps a combination of exhaustion, frustration and resentment towards Cliff pushed her over the edge. In the end I think she didn't want it enough. She seemed to feel that she had achieved enough by getting that far and now she was tired and pissed-off and wanted to go home. I know I've said this before, but this competition is extremely stressful and requires a lot of stamina to stay the distance.... You have to want it really badly. I also suspect that Mia felt that she was not likely to win the competition and so would rather quit than eventually be fired -- she is clearly a very proud person. I think she made the wrong decision but at the time it was also good to know that she was going home to her family and a decent night's sleep.