Although he had lived for more than five hundred years in his previous life, aside from Mo Qingxue, Tang Yi had never really had a romantic relationship. He could be considered a novice in matters of the heart, and was caught off guard by Jin Yan's sudden confession, unsure of how to respond.
In the end, Jin Yan still left. After crying and pouring out her feelings and love, she didn't wait for Tang Yi to say anything before she turned around and left.
Jin Yan had originally planned to keep her love for Tang Yi a secret within her heart, as a secret to herself forever, but somehow, she ended up confessing her feelings to him.
But Jin Yan knew that Tang Yi had Mo Qingxue, and being a newcomer, she couldn't ask him to abandon Mo Qingxue and be with her. And since she didn't want to share Tang Yi with another woman, the only choice left for Jin Yan was to step back on her own.