She saw her chance and took it.
That's what strikes me as having been so fine.

But of course," he wound up, "he liked her first." "Naturally," said Strether.
"I mean that they first met somehow and somewhere--I believe in some American house--and she, without in the least then intending it, made her impression.

Then with time and opportunity he made his; and after THAT she was as bad as he." Strether vaguely took it up.

"As 'bad' ?" "She began, that is, to care--to care very much.

Alone, and in her horrid position, she found it, when once she had started, an interest.
It was, it is, an interest, and it did--it continues to do--a lot for herself as well.