I'm actually happy that he is leaving, he needs to go home and tie up loose ends so he won...

Where did it say he was leaving he still hasn't made up his mind

If you've read enough yaoi's, then you can see the foreshadowing in the webtoon. He's going to leave but that's not going to break their relationship.

EXACTLY!

I know that eventually the manga will have a happy ending (hopefully!! Like God damn it, there's always this fear that the author is a sadist or loves sad endings.... usually it doesn't happen like that... but there's always that snowflake *Shudders*)
anyway, hopefully it will be he returns home, then eventually decides to return back to Caius .

I've also bought the raws, and here's what I understood based on them + twitter:
spoiler ahead:
.

.
.
.
.
So basically, I'll start with the scenes,
there's a scene where Caius uses his powers to bring a butterfuly from a tree to Kōichi , he talks a little then returns it back.
I think he was saying how even if something so beautiful (the butterfly == refers to Kōichi) and precious it's not right to take it from it's home.
So He probably made up his mind about returning Kōichi back home.
But that's how I interpreted the scene

Anyway, I think Kōichi decides to return "temporarily" to resolve his life there, and he Caius spend a night together for the last time and next day Caius takes him to a gate to take him home ......

However, it seems Caius was lying to Kōichi.... he wasn't going to return him temporarily, but rather he wanted to erase his memories and release him back... losing him for good.
(I HAD A FREAKING HEART ATTACK AT THAT! WHYYYYYY)

anyway, in the last two chapters, the other giant with glasses and werewolf somehow enter through the portal to warn Kōichi while he was travailing through it. The glasses dude passes him a magical circle, and in ch39 Kōichi walks through shards of memories.... now I don't know if they were his or Caius, but I think they're Caius because there was the scenes about Caius chidlhood, stuff before Kōichi came to his world, and what seems to be the conversation Caius had with the glasses dude about erasing Kōichi memories and returning him home for good.
The chapter ends with Kōichi (I think) crying.


NOW MY FREAKING QUESTION, will we get chapter 40 next week or not?? I don't know how Japanese manga updates, I heard on twitter that it will continue in January-2021....... If it's correct, then kill me now because I can't wait..

why the freak do I always read ongoing work??? WHYYYYYYYYY