Ritsuko’s mouth is smiling but her eyes look lonely.
Kendrix: At this point, she's wishing Gendo was a little less "clumsy".
Also, another of those powerful, iconic lines and a rather original way to discribe some socially withdrawn person's barely-existance as she doesn't understand how the world around her, those invisible rules of human interactions, and even how her own heart works, with all those things that some would caracterize as what makes life worth living passing her by.
This might mislead one to think that Ritsuko is sympathetic to Rei, but that's her rational mind speaking, telling her that she shouldn't be jealous of a teenaged girl, but she's averting her eyes/lying through her teeth, as we later learn that she is not free of blame for what has been done to Rei and ultimately has an irrational hate towards the poor girl.
UrsusArctos: Ritsuko really seems sympathetic to Rei (and Gendo) at this juncture. And that line probably says a lot about Gendo's own living conditions. Well, maybe not as squalid as Rei's apartment, but I'm sure it's no more inviting.
Sailor Star Dust: A sense of pity for Rei (and Gendo), perhaps?
Cody MacArthur Fett: At first Ritsuko's statement seems to be a reference to Rei's rather insulated social habits, but the statement becomes much more frightening in episode 25 when we find out that Rei is borderline suicidal:
TEXT: "It frightens you, doesn't it?"
REI 3: No, it makes me happy. Because I want to die. What I desire is despair. I want to return to nothingness.