the elephant in the room

Jennifer WeinerのFly Away Homeを読んでいます。
“Dad,” Lizzie said, a little impatiently. “I want to talk about Dad.” She also wanted to talk about Diana’s frequent absences from the house on Spruce Street, and why her sister had been sleeping on the couch in the living room instead of in bed with her husband, but she’d decided to start with the elephant in the room.
"the elephant in the room" は1/15/2011に取り上げた慣用句です。おさらいします。
・Oxford English Dictionary: A major problem or controversial issue that is obviously present but avoided as a subject for discussion because it is more comfortable to do so.: It's the elephant in the room that everybody avoids talking about, isn't it?
World Wide Words: It refers to some a problem or controversial issue that’s obviously present but which everyone ignores or avoids mentioning, usually because it’s politically or socially embarrassing.
"the elephant in the room" の由来についてはWorld Wide Wordsに詳しい説明がありました。