Chu Muchen was the Third Prince's study companion and had been childhood friends with Yun Zhenzhen. He planned to ask the emperor for her hand once she came of age, but war suddenly broke out at the border. Before he could confess his feelings, he had to leave for the front. When he returned, he learned Yun Zhenzhen had been promised to someone else, so he had no choice but to bury his feelings and keep his distance.
Yun Zhenzhen had loved someone since childhood, which was why she was always following her Third Imperial Brother around. She was angry when she learned he had gone to the border without telling her and had not contacted her for three years. After she was promised to someone else, she was distressed, but heaven-sent luck gave her the perfect chance to get out of the engagement.
A little scene:
“Who did you say had their engagement called off?” Chu Muchen's eyes went wide.
“Princess Roujia. Princess Roujia. Princess Roujia's engagement to Cheng Jinzhi has been canceled.” His friend looked at him with disdain as he repeated it three times.
“Quick, quick, quick! Bring out the biggest firecrackers. I'm celebrating today!” He didn't even wait for his friend, heading off toward his room with a grin.
His friend asked, bewildered, “Where are you going?”
Chu Muchen said mysteriously, “You don't think it'd be too much if I went to check on the princess, do you?”
With the corners of his mouth impossible to keep down, Chu Muchen ran to the princess's residence.
Yun Zhenzhen: ...
On the day he asked for her hand, Chu Muchen was grinning from ear to ear as he smugly raised his eyebrows at Cheng Jinzhi. After they married, he did everything Yun Zhenzhen asked, without question.