How we cite our quotes: (Chapter.Paragraph)
Quote #7
A whole series of events – Thérèse's passionate caresses, the feverish drama of the murder and the fearful expectation of sensual pleasure – had driven him more or less insane [...]. From then on, Laurent had lapsed into the intolerable existence and endless horror in which he was now entrapped. (22.4)
Laurent's feeling of entrapment is a direct result of a "whole series of events." See, in Zola's scientific, deterministic mind, everything is related.
Quote #8
At times, seeing the murky glows around her and smelling the acrid scent of damp, she imagined that she had been buried alive and thought she was in the earth at the bottom of a communal grave, with the dead milling around her. The idea calmed her and consoled her. (24.6)
After Camille's death, Thérèse realizes that she still hasn't escaped the narrow confines of the shop. Similar to the beginning of the novel, when she hallucinates that she's being buried alive in a vault, here we again see Thérèse imagining that she's being buried in a grave. However, a significant shift has occurred. Whereas before Thérèse felt an uncontrollable need to escape the claustrophobic space of the shop, now Thérèse finds comfort in the idea of being buried. How depressing. She's stopped wishing for something better, and now just accepts her misery.
Quote #9
But they did not dare, they could not escape. [...] A sort of attraction and repulsion drove them asunder and kept them together at the same time. (30.7)
Despite the fact that Thérèse and Laurent hate being around each other, they find themselves unable to stay apart. Can't live with him, can't live without him, we guess? Their inability to escape each other's company places such an extreme amount of pressure on them that it leads to disastrous results. Like murder. And then double-suicide.