At the beginning of The Stranger, Mersault had no friends, family, and had a job he hated. Though it seemed like Mersault didn’t mind being isolated and enjoyed spending time alone, this disconnection from the world really harmed him in ther long run.
In the first chapter, we learn that Merault’s mother died, yet he feels no emotions towards her death, and the realtionship between Mersault and his mother was strained before her passing. Mersault is so impartial to this death, that as soon as he gets back home from his mothers’ funeral, he meets up with a girl Marie, and Marie instantly feels connected to him.
Though Mersault and Marie end up spending a lot of time together, when Marie proposes to Mersault, he remains very casual and disinterested. Receiving a marriage proposal is obviously something that most people would get very excited about, so Mersaults reaction, or lack thereof, proves that he is detatched.
All of this emotional disconnection from the world ends up being a bigger deal when Mersault kills a man and feels no remorse. The prosecutor ended up bringing Mersaults disinterest towards his mothers death and other examples of his emotional detatchment to convict Mersault guilty enough to receive the death penalty. When Mersault finds out that he will be sentenced to death, he still has no reaction, which proves his extreme detachment from society and the dangers that come with being disconnected.