I swear of god I've read the last five chapters but I can't get it. Did I miss something?!...

Because deep inside Yujin is also catching feelings and this wasn't a part of the contract, Aaron did everything to get him a role where he can sing, he is trying to make him famous for his singing and this always been Yujin dream but he got past trauma from his dad. So in the end he reminded Aaron that they are not a thing since Aaron is acting like his real man instead of a fake BF.

Thanks for explaining