Holden is emotionally distant from his mother. The loss of her younger son has locked Mrs. Caulfield in a state of nervous exhaustion that is characterized by constant headaches and anxiety which causes her to lose sleep and chain smoke.
Holden knows that his mother has not gotten over the death of her youngest son, so she is still grieving, which leads the reader to understand that she is sad.
In Chapter 7, Holden describes how his mother will react when she finds out that he has been kicked out of another school. He wants to arrive home after his parents have received the letter from Pencey Prep indicating that Holden has been expelled.
"I didn't want to go home or anything till they got it and thoroughly digested it and all. I didn't want to be around when they first got it. My mother gets very hysterical. She's not too bad after she gets something thoroughly digested, though." (Salinger)
In Chapter 21, when Holden sneaks into his apartment, he talks about his mother again. Holden tells the reader that his mother is a light sleeper, she can hear a pin drop a mile away.
"You can hit my father over the head with a chair and he won't take up, but my mother, all you have to do to my mother is cough somewhere in Siberia and she'll hear you. She's nervous as hell. Half the time she's up all night smoking cigarettes. (Salinger)
Holden doesn't have a very good relationship with either of his parents. He can't confide in them. He has not opened up to anyone about his grief over his brother. He sneaks into his apartment and listens to his mother scold Phoebe, while he hides in the closet, he can't even confront her, he doesn't trust her.
Holden believes that his mother is in a fragile state, suffering from a nervous condition with constant headaches is how he describes her in Chapter 23. Holden's mother is so grief stricken over the death of her son, Allie, that Holden feels really guilty about being such a burden to her, that is why he doesn't go home right away and that is why he chooses to hide while in NYC rather than go home, even after he has no where else to stay.
The only person in the book that Holden has a genuine relationship with that is based on trust and real love is his little sister Phoebe.