The woman has a secret that she decides to take it to the grave. -Mother who continues to hide his son's blood type

My first wedding anniversary was a countdown to divorce. My husband and I made a promise. If you have not had children after two years of marriage, you'll get divorced. However, even after a year, I was not blessed with children, and before long, the promises from the couple became my own. Why am I the only one doing my best... I don't want to break up with my husband... because the two years I dedicated to my husband will be wasted? One day, as I kept asking myself questions, I found a secret that I had decided to take to the grave...