Why Is the Marquis Always So Oblivious to Romance?

Why Is the Marquis Always So Oblivious to Romance? Plot:

Su Wanyi, a young cook in the Marquis Mansion, has a secret crush on Gu Zhaonian, the cold and stern Marquis. The jade hairpin she saved three months' salary to buy was taken by him as a pin for hanging dishcloths in the kitchen; the osmanthus honey pear paste she stayed up all night to make was given by him to a servant's sick child; even when she invited him to the back garden on Qixi Festival (Chinese Valentine's Day), he held a military book and said, "The border is unstable recently, I need to study tactics." Su Wanyi grows more determined despite setbacks, until one day she catches the Marquis staring at an old portrait—the woman in the portrait looks seven points like her? It turns out that the Marquis's oblivion to romance hides an old wound he dare not mention, and Su Wanyi's appearance is slowly melting his frozen heart...