I remember there were some leaked script informations mentioned that Lingling has depression because of his past experience, so he was introverted and difficult to get close to others. Before he met Ruan, his only friend was his roommate. But things started to change in this door - especially in next episode, he was willing to accept Ruan's care for him🥺. I love this door very much, plots are great and it's like a sweet start of their further relationship.