
I understand your point that Heesung *might* not be the right guy for Dan. But I don't agree w you saying Hessung is trash. He hasn't done anything harmful to Dan in the story so far and he's doing his best to appeal to him in his own way (E.g., giving an excessive amount of gifts). That's already a huge point for me to prefer Heesung.
If we're going to nitpick Heesung's character and compatibility w Dan, then Jaekyung should certainly be the first person to criticize. If Heesung lacks the consistency, then Jaekyung lacks the empathy to sympathize w Dan. But the ML isn't rlly the main topic of this discussion. My two cents.
In a previous chapter, Heesung's minder said that he's fickle and falls in and out of love and love bombs people, which is what he's doing to Dan. I think it's the thrill of the chase for him and he's able to abruptly move on from Dan. Potato sees right through him.
I'm not saying Dan's relationship with Jaekyung is healthy either. But I can't see Heesung taking the initiative to visit Dan's grandma (without turning it into a photo op anyway), rescuing Dan from the loan sharks, paying his debt and his grandmother's hospital bills. Jaekung says that having Dan live with him is not to help Dan but for selfish reasons, but regardless of his motives, he has a constancy about him that Heesung clearly lacks.