DC goes to school and sees Mr. Mell fired. He leaves school, and doesn't see anyone from there for a long time. He works, and seems to disappear from his own life; eventually, he runs away and really does disappear from it. He finds his Aunt, and Mr. and Miss Murdstone come find him, but finally they leave again and he's glad, for the first time in the novel, to see anyone who leaves gone. Later he sees Mr. Wickfield slowly losing his mind.
The worst kinds of leaving for DC, though, seems to be committed by women. When Emily Peggotty runs away from home with Steerforth, it's a HUGE problem. Everyone is worried that Em'ly will become a whore in London, but no one will say this directly. (Earlier, a woman--her friend Martha--ran away from home and seems to have become a whore in London, but she's also a very crazy and apparently unattractive whore, so it's hard to tell.) Pages and pages and pages are spent mourning Em'ly and worrying about her and wondering if she'll ever come back. (Meanwhile, Mr. Spenlow and Mr. Barkis have both died, but their disappearances weren't nearly so hard. DC seems more worried that Agnes is going to marry Uriah Heep and so disappear from his life, even though Agnes swears she'll never marry Uriah.) Likewise, Dora is now about to die, too, which DC has to keep worrying over, hinting at it and alluding to it and anticipating it--then he takes a couple chapters to talk about other people, so that the narrative is left dreading her death.
All the women are going away. Men like Mr. Peggotty have to follow women around, to make sure they don't disappear, because leaving home, in any way, means becoming a whore. (Whores are TERRIBLE, although the novel won't talk about this clearly enough for me to tell why.) Death is probably whores too.
