There are so many layers of masking and disguise in this passage that I can't stop thinking about them.
First there's the literal mask: Shi Ruyi wearing that yellow dress she's never worn before, deliberately making herself look worse, trying to present a false version of herself to Wen Youan. But the irony is that her 'ugly' choice actually makes her look 'much more lively' according to Guyu. So her attempt at self-sabotage backfires. She can't even successfully hide who she is.
Then there's the mask of the lie Wen Qing tells. She pretends Shi Ruyi will visit when she never promised that. But the deeper mask is her entire persona at court—always composed, always the loyal general, never showing her true fears about her son's future.
The name symbolism is gorgeous though. 'You'an' means peaceful/safe. Her entire hope for her son is encoded in his name from birth. 'I hope I can bless you with a peaceful life. Your father and I will be satisfied.' But the cruel irony is that by being involved with someone like the Crown Princess, he's moving AWAY from that peaceful life. His name is a prayer that his choices are actively undermining.
And the color yellow—usually a color of royalty, of the Emperor—worn by both Shi Ruyi and Wen Youan without either fully understanding what it means. Shi Ruyi wears it to appear unappealing; Wen Youan wears it because he subconsciously wants to be matched with her. The color becomes a bridge between them that neither can see.
The text also keeps returning to eyes and sight: Shi Ruyi can't see her mother's guards, Wen Youan's eyes 'light up,' Wen Qing's 'dark circles,' the way characters look at each other or avoid looking. Sight and blindness as metaphors for understanding and ignorance runs through the whole passage.