"Edna and her father had a warm, and almost violent dispute upon the subject of her refusal to attend her sister's wedding. Mr. Pontellier declined to interfere, to interpose either his influence or his authority."

"Edna and her father had a warm, and almost violent dispute upon the subject of her refusal to attend her sister's wedding. Mr. Pontellier declined to interfere, to interpose either his influence or his authority." - page 79

Mrs. Pontellier does not want to go to her sister, Janet's wedding. Obviously her father expects and wants her to attend because clearly, its her sister and expectedly she should be there. Maybe at this point Mr. Pontellier does not interfere because maybe now he know she basically marches to the beat of her own drum and it will not matter what his input is because its her desicion and she plainly does not want to attend.