When the knight's away, the apprentices will play—the saying went something along those lines.
With her father no longer there, there was a sense of freedom she felt to no longer having him hawking over everything she did. It wasn't as if she was that much worse behaved, but he required a level of perfection that she found exhausting after a while.
It was almost as if he had to ensure she was doing perfectly well to convince Rochelle that everything was alright with Irene being an apprentice and trying to become a knight.
It made Irene wonder if her mother knew that she had been wounded at the beginning of the winter or if he had omitted that information from her so she wouldn't appear on the Duke's doorstep herself.
Regardless, the knights and mages continued to hold secrets with one another as monsters appeared and Irene found it grating. She knew that Felix did as well.