They are two different characters. In the previous life, Demon King Hong Ye is inlove with Princess Ning An from human race but she killed him on their wedding causing the demon race to fall from grace. Hundred years have passed and Xiao Yao, who had the same face as Ning An accidentally unsealed Hong Ye's soul in an incident, causing him to awaken. He then vowed to make the demon race rise again and so on. For the two characters being inlove with Hong Ye (if Ning An truly loved him in the previous life), I mean you can say that but it's not bothering me since they both have the same face and it's possible that there's more to it than we know like what if Ning An did that to save Hong Ye in the previous life. The possibility is endless....
WARNING: POTENTIAL SPOILER?So in Red Moon Pact, the ML told us how the FL of Love Pavillion died...Reference:…
I have long accepted the ending for the casts of this trilogy but it's understandable to the likes of you who accidentally got spoiled to have this kind of reaction. LIP is the prequel of the trilogy. It should have come out first but the production team had other plans.