Agreed about Chengzhi and Ah Jiu. There's the feeling of "what if?" but they could not have ended up happily together as they were.

I didn't like how it seemed like Wan Jiao'er just married her senior because she knew Chengzhi loved Qing Qing. Before falling in love with Chengzhi she seemed like a much more independent character. I think the relationship between Chengzhi and Xiao Hui is more of a brother and sister relationship than a romantic one. It's reminiscent of the one between Zhang Wuji and Yang Buhui in HSDS, they knew each other when they were little and remained friends (and nothing more) even as they grew up.