Okay...

this is exactly what i was thinking

he probably will meet both and end up with yahwi lol

I don't know at this point. Throughout this whole series, Cain felt like he was supposed to be from another story altogether and was used here instead because there was such backlash against Yahwi. Personally, I like Yahwi. Yes, he made some bad choices, but he's young and has some serious trauma and introspection to deal with. When you don't cope with your trauma and instead push it away, it can come out in uncontrollable ways. Jooin also was too immature to handle someone with trauma, or even love at all because he didn't know what he wanted, nor how to love himself. All in all, none of the characters knew how to compromise or what they wanted out of a relationship, how to maintain a healthy relationship, how to communicate, and how not to lose themselves in the process. While all this is very common, most people go through those emotions in high school when they start dating or when they have their first love. None of these three did, which allowed for an explosion of emotions.
While the growth for the characters was very realistic, and I originally thought that there would be a year or two break for Yawhi and Jooin to grown up and come together again with a stronger foundation, because the author had Cain present that ring, I don't feel that will be the case anymore. I believe wholeheartedly that Yawhi and Jooin could make it work as long as they have open communication, keep their boundaries and learn to compromise with each other, I don't think the author will go that route because of how much hate he got. He's not a toxic individual by any means. He's a good person who made bad choices because he could handle his fear and emotions. Cain, on the other hand, while full of love and compassion, was trying to leash Jooin and use his hurt over Yahwi to get his heart. That never works. Rebounds never last and Cain will always be someone that Jooin would be settling for, no matter how sweet he is. And they both would know that, which could lead to resentment from either or both down the line, or just a general dissatisfaction. I do hope he ends up with Yahwi if he ends up with anything at all, but the safest option for the writer is to leave it open ended.