If I had to find one flaw of the work, it is that the relationship of the 2 main leads never really encounters any truly difficult challenges which would require some sort of sacrifice on the part of either one. It gives it a bit of a fairy tale feel though I understand that the author never meant for this novel to be anything overly serious.
For example, she gives birth to a healthy male heir right off the bat. Imagine the pressure He Heng would have to face to have children with other wives if she is not able to produce an heir for even a few years! I doubt he would be able to stay completely faithful to her in such a case.