Because you have a crush on him?

Guan Xian does what he said to Xia Sha. In the vintage store next door, he goes straight to Xiao Ni without even glance at Xia Sha again. 

She keeps reminding herself that he come here not for her but for his little sister. She shouldn't felt bad for not talking to him even though they are in the same room.

But the gloomy mood still wins over her.

A weird mixture of irritate and sad feelings ruined Xia Sha's mood to shop today. With a frown, she walks to Kai Xin like a sulking kid. "Let's go home," she said flatly. 

"Whew, what's wrong with that face? Talking with your prince charming makes you angry?"

Kai Xin put down the Santa's hat back to the rack, Guan Xian and Xiao Ni's laughter become their background. It's not like Xia Sha is jealous of them together, not at all. 

She is just annoyed by how Guan Xian act.