How we cite our quotes: (Book.Chapter.Paragraph)
Quote #1
Oh Walter: did he know that the most intriguing thing about him, in the months when Patty was getting to know him, was that he was Richard Katz's friend? Did he notice how, every time Patty saw him, she contrived to find nonchalant ways to lead the conversation around the Richard? Did he have any suspicion, that first night, when she agreed to let him call her, that she was thinking of Richard? (2.2.320)
This is deceit. Just because Patty does a lousy job of pretending otherwise, and Walter knows full well that Richard is irresistible to women, doesn't mean it isn't dishonest. In a way, Walter becomes complicit in Patty's lies, by not trying to communicate with her about their relationship. When he finally attempts to deal with it, in Room 21 in the Whispering Pines, the effort overwhelms him, and he ends up crying and shaking and pacing and all kinds of unpleasant stuff. Better to talk about things in the beginning, no?
Quote #2
"Look," she said, "you have to swear not to tell Richard," although she realized, even as she said it, that she'd never quite understood this prohibition, "but Eliza has leukemia. It's really terrible."
To her surprise, Walter laughed. "That doesn't seem likely."
"Well, it's true," she said. "Whether or not it seems likely to you."
"OK. And is she still doing heroin?"
A fact that she'd seldom paid attention to before – that he was two years older than she was – suddenly made its presence felt. (2.2.394-397)
Why does this conversation cause Patty to realize that Walter is older than her? Maybe because it shows her naïveté – that she is too easily trusting. and life experience (that is, experiences like these) will make her more wary of believing people, and bring her to expect the worst of people (specifically, to expect people to lie).
Quote #3
"Here's the choice," Richard said. "We stop now, or you leave Walter. And since the latter is not acceptable, we stop now."
"Or, third possibility, we could not stop and I could just not tell him."
"I don't want to live that way. Do you?"
"It's true that two of the three people he loves most in the world are you and me." (2.3.431)
Wow, Patty doesn't even answer the question. Richard, on the other hand, either has a strong moral fiber that makes lying to Walter out of the question, or has enough experience with deceit to recall the corrosive impact it can have on one's body and mind (nightmares, ulcers, etc.).