The Wallfacer concept was extremely interesting to me initially, but I'm almost a third of the way through this book and it just feels like a very unconsidered first draft. Many of the new characters are very one-dimensional and speak in painfully caricatured dialogue. And then when I started having to wade through page after page of Luo Ji being obsessed with his manic pixie dream girl, except she's not manic because she's so sophisticated and sensitive and like a fragile lily, unlike all other women who are coarse and gauche... ugh. 

I'd love to think this is maybe some elaborate plot device and will eventually be revealed as some sort of galaxy-brain Wallfacer ploy, but... the most parsimonious answer is just that these characters aren't good.