She didn't pretentiously say it was a piece of cake because that would not only be fake but also disrespectful to Yin Nan. The level of gratitude they showed her indicated how important Yin Nan's identity was, how crucial life was.
To say it's a mere piece of cake, isn't that belittling them?
How could someone's life be reduced to something as trivial as a piece of cake?
Moreover, having the Yin Family owe her a promise was really necessary for Nan Fei. Even if she didn't need it now, who knew about the future? What if she encountered an unsolvable problem later on, and it came in handy!
Of course, she hoped she would never need to use it.
"Is Bei Jiang alright?" Even though Nan Fei already knew, seeing such a horrific car accident still had her heart in knots. She couldn't rest assured and asked again, "If something happened, don't hide it from me. I can handle it."
The thing she feared most was people thinking it was for her own good and hiding problems from her.
