"Borrowing" or Plagiarism?

At first I thought, what's the big deal? How does someone not use parallels to other popular works in their novels? How many unique stories can you write about the same topic?

But, then I read this:

Harvard Novelist Says Copying Was Unintentional
By DINITIA SMITH
Published: April 25, 2006

And the borrowings may be more extensive than have previously been reported. The Crimson cited 13 instances in which Ms. Viswanathan's book closely paralleled Ms. McCafferty's work. But there are at least 29 passages that are strikingly similar.

At one point in "Sloppy Firsts," Ms. McCafferty's heroine unexpectedly encounters her love interest. Ms. McCafferty writes:

"Though I used to see him sometimes at Hope's house, Marcus and I had never, ever acknowledged each other's existence before. So I froze, not knowing whether I should (a) laugh, (b) say something, or (c) ignore him and keep on walking. I chose a brilliant combo of (a) and (b).

" 'Uh, yeah. Ha. Ha. Ha.'

"I turned around and saw that Marcus was smiling at me."

Similarly, Ms. Viswanathan's heroine, Opal, bumps into her love interest, and the two of them spy on one of the school's popular girls.

Ms. Viswanathan writes: "Though I had been to school with him for the last three years, Sean Whalen and I had never acknowledged each other's existence before. I froze, unsure of (a) what he was talking about, or (b) what I was supposed to do about it. I stared at him.

" 'Flatirons,' he said. 'At least seven flatirons for that hair.'

" 'Ha, yeah. Uh, ha. Ha.' I looked at the floor and managed a pathetic combination of laughter and monosyllables, then remembered that the object of our mockery was his former best friend.

"I looked up and saw that Sean was grinning."

Better luck next time, Ms. Viswanathan?