C242 Our first time

What did Yun Er mean by leaving her bank card here? What did she write? I quickly picked up the letter and started to read:

"microgram, when I was writing this letter to you, you fell asleep in the living room. You are asleep, snoring against the back of the sofa, I know, you are tired, you are tired, your body is tired, your heart is tired! I'm not sleepy. I'm writing you this letter