Great drama. There is btw indeed a clip that wasn't translated, but you can find it on TencentVideo. I guess it is an alternative ending of sorts? So you can interpret it as happy ending, if you want.
Watching episode 5... So far Zang Hai he seems like a clever, righteous hero to me, punishing evil and saving the innocent. Not my favourite type of character, but whatever. At least there are chances he will not die in the end as a result. Production quality is insanely high.
I suppose it does. As a subplot. At least according to baidu wiki: "In the course of events, she and Zang Hai meet, get to know each other, initially use one another, then come to understand each other, and ultimately, develop feelings for one another."
So fl's family was really at fault or was it all a misunderstanding?, if not why did the wei family even agree…
From my understanding, they were partially at fault because, as allies, they were probably supposed to help them, but they didn't for political reasons and because they didn't want to fight and die as the situation was not good for Wei family at that time anyway. The reason why they decided on the marriage 14 years later is very simple: politics. It's not unusual in history for countries to be allies, then enemies, and then allies again.
I mean, I only watched 4 episodes, but so far the story is rather simple. Decent enough to keep my attention, sure, but no more than that. Lots of popular actors, top-notch CGI, but otherwise I don't think there's anything special about this drama. Maybe my expectations were a bit too high, well, whatever.
I like it so far. Obviously, I doubt much of this is historically accurate. It also has a lot of simplifications, for example, most villains here are rather one dimensional characters, and khitans are portrayed as some kind of orcs. But it's a decent enough drama to watch if you don't try to think too deeply...