[SPOILERS] CLICK HERE to Read a Very Long Ending Explanation

 marquise:

I think its a matter of perspective. Shi Ying is a true hero, heart and soul. So how can he resign himself to "just" live a happy 27yrs life with Zhu Yan? For me it doesnt make sense. At least it doesnt match with my understanding of what a pure cultivator should aim for & diminishes the awe I always feel for this type of hero. And the drama gave it to me all hahaha - the hero saves the world, he is not dead (cause xianxia) and there is an open door for my imagination to go wild about their future together. This, for me, is a happy xianxia ending.

"I wonder how many people who were here at the beginning of this drama are still camping on this discussion page to see this lol." I am still kinda camping XD

I love everything you said and I think it's very interesting how personal preference plays a big part in determining whether the ending is happy or not. Those who highly banked on the novel ending of them living out their mortal lives kinda confined themselves in what is considered the best happy ending for the couple because happily ever after is so cut and dry...as in there is nothing to argue about if everything is fine and dandy. So any other ending  besides that automatically goes in the sad/bad ending category that doesn't deserve the time and effort to try and rationalize as an alternate ending. I mean I can see where this side is coming from because this couple went through so much that a happily ever after would be therapeutic to the characters and the viewer. I just argue that growing old together doesn't have to be the ONLY payoff destined for Shi Ying and Zhu Yan. The drama really went their way to tease their reunion using the laws of xianxia so it really depends how flexible the viewer wants to be. At least in the drama there were too many signs and foreshadowing of Shi Ying's fate that following the novel ending would have made those writing decisions redundant. 

That's why I found Xiao Zhan's interview answers intriguing because his major takeaway is that Shi Ying was the happiest protecting the world with his loved one and I think that is the mindset to have for the drama adaptation that seems to be very different from the novel. He really understands that heroic selfless nature of Shi Ying and sees him for his accomplishments and legacy. I like how the drama makes it so peace will last for future generations to come thanks to Shi Ying and Zhu Yan's good deeds. They will definitely be cemented as legendary cultivators in their world.  

 Niwa Nakajima:

I laughed, screamed, and was moved almost to tears while reading your theory.  You really examine it with a great perspective that I haven't seen in other people's comments.  I am very grateful for this theory.  My dissatisfaction after watching the end of the drama was finally fulfilled and I reached the point where I fell even more in love with the first xianxia drama I watched.  Maybe in the future I will never love a xianxia drama more than I love this drama.  The open ending that initially traumatized me, now actually makes my heart feel warm.

Thank you so much for taking the time to read my long essay! I can imagine how heartbreaking the ending is on first watch, I was also in the same position. I stand by my belief that this drama was always meant to be discussed and analyzed thoroughly amongst viewers to figure out the true meaning behind the story. But a lot of people these days are too quick to move onto the next drama or they are too caught up in their emotions to want to comprehend what they actually watched. I respect any viewer who feel like there is more to the story than what is presented to us at first glance. 

I really like the open ending because it reflects the drama's recurring message that we should be more optimistic and open-minded and not be swayed by the bleak nature of things.  The Longest Promise being your first xianxia drama is pretty crazy though haha because as you can tell from my essay it is not the most straightforward story suited for first-timers.