War and Peace Volume 2, Part 4, Chapter 13 Summary
Soon after the holidays, Nikolai tells his mom that he’s going to marry Sonya. She is devastated and tells him that he can legally do whatever he wants, but she will never accept Sonya as a daughter-in-law. She then calls his dad, who is quiet and embarrassed and quickly ends the conversation.
A few days later Countess Rostov reads the riot act to Sonya, basically calling her a tramp and accusing her of being a gold-digger. Yikes. (Why's the Countess so mad? Because Sonya is just a penniless relative who has been living with the Rostovs out of charity.)
Nikolai bursts in, demands that his mother back down, and then almost tells her off for good. Natasha comes in and quickly calms everyone down, at least to the point of bare civility. Their mom promises to lay off Sonya, and Nikolai promises not to marry her in secret.
Nikolai goes off to his regiment, planning to resign his commission and come home to settle down.
With him gone, life is pretty miserable at the Rostov house. Countess Rostov can’t help but be really mean to her niece. Meanwhile, Natasha is going nuts with Andrei’s absence. His letters make her mad and she writes boring, perfunctory ones back.
Finally, at the end of January, Count Rostov takes the girls to Moscow to meet up with Andrei and Nikolai, while the Countess stays at home sick.