I would’ve stayed.

Well yeah truth to be told, it would be the same either way. But Koichi saying that because he thought that it would be meaningless because if he stay, then his existence in the real world would erase or died, r8? I think he's just trying to say that if he had to die in the real world because he stay in the titan world, then it would be too painful story because her mother sacrifice for him in the real world. U kno, especially for his relatives that still alive in the real world. *just my opini*(￣∇￣")

The world would see it as meaningless because that is the way it would be rewritten, even though Koichi won't see it like that, he probably thinks is unfair for his mom to have her existence rewritten.

And the other option is that his existence would be written as if he died shortly after his mom, which is cruel too, for his mom and for all the people he knows.

He expected to not have his existence sacrificed in the real world in exchange to have his mom and dad alive, since he can't have that, he wants to come back.

I don’t really understand the thought behind that. Coming back exactly bc your family can’t be revived doesn’t make sense to me. Like I can understand if you "exchange" your life for your parents' life, also it would make sense to want to come back if you could see your family again but if I remember correctly there isn’t anyone really any family or loved ones waiting for him in his world. Why would he throw away the love of his life and a whole race of another world just bc of what other people could think?
And it’s not like anything drastic would change in his world since that law thingy won’t allow that.

To Kouichi's world it won’t matter what he does, whether he goes back or not, nothing significant will change.
But for the titans’ world it makes a huge difference. Kouichi staying there would bring prosperity and happiness to the titans (especially Caius would be more than happy), while him going back would mean the loss of the bride, the loss of a loved one and a whole lot of sadness for Kouichi when he realizes that home is not a place but a feeling, and that he lost it when he went back bc Caius is his home now.
For real, I’m just hoping that there is a manga out there that punishes bad decisions, like I’m almost 100 percent sure that if Kouichi went to his own world, Caius would find a way to bring him back.
It’d be refreshing to read a manga where (in this case) the uke wouldn’t ever come back and regret his decision to the day he will die.

He has an uncle, and friends, specially that guy who was there since kids who he is very close to, you have to understand, Koichi is selfless, he does not the world to see his mom as a meaningless sacrifice, and if his own sacrifice can't bring his mother then he does not want to do it, it would be all for his own good.

I would personally stay, and I do admit is because I'm selfish, I would think only on what's the best and more convenient thing for me, I wouldn't care THAT much how the world sees my death mother, or how my friends would cry for me because I would only think of myself , at most I would rationalize this with "this is what my mother would have wanted" and get over it.

But Koichi is selfless, he DOES care who the world would view his mother and thinks of that as unfair for her.

Oh, probably Mo Dao Zu Shi would be of your taste, he does regret everything until his grave, and beyond that, the main theme is action tho not so much BL, although SPOILER alert: it is tragedy but there is a happy ending SPOILER

"The moon that rises in the day", but is shoujo not BL, Halita one of the main character regrets even after her death the decisions she made towards the one she loved, and how she wronged him.

And "Cheating men must die" also has that kind of satisfaction of having a character regretting failing to their love.

"Momentum" I haven't finished but it seems to go where you wanted it

"Eunsoo" but is mainly straight romance.

I remember reading some, but I can't recall the names, sorry.

There is probably more under the tag of "yaoi and tragedy"

Thank you for the recommendations, I will definitely check them out ٩(๑❛ᴗ❛๑)۶

I think if I was in this situation I’d always choose Caius' world bc rationally speaking the titans would need my presence more than the people in my old world.
And I completely forgot about his uncle. I do remember his friend but I didn’t get the impression that they were really really close but my memory could also just fool me again ╮(￣▽￣)╭

You are welcome.
They were pretty close, there this scene when Caius is talking with his childhood friend and Koichi sees himself and his friend in them and cries, it also says how his friend saved his life when he was sick and how he was the biggest support when his mom died.