Idk. The thing is yahwi is portrayed like the lesson of this manhwa and a typical behavior that you will meet throughout humans while cain(even tho I love him) is not natural at all. And there will never be someone like him. He's just like a robot and looks like he doesn't have a personality an opinion so ofc you'd choose him. You can compare Cain with whoever character you want you'll always end up seeing he's best because he's just perfect. But perfection shouldn't exist. So the best ending would be yahwi x Cain
he has a personality and flaws as well though but we havent seen too much of it yet, and idk about you but caring and patient men do exist
naur the majority of my reply git cut off rip
but yeah point is, cain was just really desperate for jooin who was already entangled with someone and went above and beyond so he could be noticed. a lot of people with one sided love so shi like that too its not unrealistic
this can either go 2 ways, he gets together with yahwi and thus is gonna be like evry other stiry where time apart somehow means theyre good for each other OR
He gets together with Cain after the time skip and this can be a rare case where the second and obviously better choice actually is the endgame