There is no O.R. open and the doctors weren't prepared for a series of events that took Nick's life in the end. Cristina tells Lexie this just happens sometimes but they do more good than harm overall.
I think it's better to have someone, even if it hurts, even if it is the most painful thing you have done, even if it's the most painful thing you've ever had to do. I think it's better to have someone.