Actually, from Isabel's perspective, there was nothing wrong with saying that.
However, when it fell on Raymond's ears, he couldn't help but frown and then corrected Isabel, "Sister Isabel, you got it wrong. Filial piety is used to describe my goodness to Father, while my goodness to you can only be love."
Raymond was good at generalizing, so as he walked hand in hand with Isabel out of the bathroom, he said to her, "By the same token, Sister Isabel's goodness to me is love, and Sister Isabel's goodness to my father is filial piety."
Isabel suddenly felt like she had dug herself into a hole, so she pulled at the corner of her lips, praised Raymond, and then quickly changed the subject: "Raymond must be hungry, let sister feed you."
Raymond's injury had improved greatly by now, and his appetite had also improved, so he ate a bit more than usual.
Isabel saw it all, feeling as if she had eaten a lot herself, and her heart swelled with happiness.