Not Villainess but the Love Cupid.

Zheng Xiang grew tired of listening to Yang Ning's never-ending blabbering. After finishing his meal, he wanted to return to the Jade Pavilion as soon as possible to avoid continuing to witness his brother's public display of affection. 

He still couldn't fathom the fact that his seemingly cold-hearted and indifferent brother, named the 'Stone-Hearted Prince' by ministers who feared his heartless and frigid approach to matters, had transformed into a devoted husband around his wife. Zheng Liang's affectionate and sweet demeanor around Yang Ning sent shivers down his spine, making him realize the depth of Zheng Liang's love for his wife.

Zheng Xiang wiped his hands clean with a napkin, casting a glance at Zheng Liang and then at Yang Ning. He spoke earnestly, "Thank you for inviting me for a meal. I will take my leave now." He couldn't bear another minute of staying with them and being force-fed with their displays of romance.