Question

My wife is never so pretty as when she is doing something she knows I disapprove of ―What did she do which he unapproved of?

Answer 1

Lavina wanted John to be a partner of Laura. So she is being sweet and pretty to get him as her partner

Answer 2

She always did what her husband did not want her to do. For example, he did not want her to spend extravagantly on fads, but she would usually take up the current fads. In order to provide for her extravagances, he had to work very hard-- as a writer, as well as a book keeper.

Second instance was, when he told her not to indulge herself in Ouija Board, she got a Ouija Board party organized at her home and asked John to be a partner of Miss Hinkle.