You had come to know very well that your boyfriend, Xiao was a really observant guy. But this...? You came across a chart with dates on his desk that looks like your... period cycle. It even came with the prediction of when the next one was going to occure.

He wasnt actively trying to chart your period. However, he had noticed that for 3-4 days every month, you'd get more moody, clingy, needy, or even sometimes you ignore him for no real reason. He started charting those dates, not knowing that it was your period. When he finally realized what he was actually charting, it was too late.

"I can explain." Xiao was still oddly monotone while talking. He was wierdly calm about this.