Tianchong means 'sweet and pampered'. It labels a light romance in which the leads, and often the male lead toward the heroine, show open affection and there is little real suffering. The conflicts are small and resolved quickly, which makes it the opposite of the tormenting kind of love story. The label can sit beside other plots, and Chinese coverage called Youthful Glory tianchong in feel even though it has a corruption storyline.
Where it comes up

Silk & Schemes
Youthful Glory: The Light Costume Romance That Starts With a Marriage of Convenience
A guide to the Mango TV costume romance Youthful Glory: a prince back in the capital to trace missing army funds, a marriage of convenience with a marquess's daughter, and what the light, sweet tone and the 30-episode run offer a viewer finding it on Netflix.