Ian already said Eunsan didn't have to step foot on an ice rink to trigger his panic attack, so it made me wonder if Eunsan has issues like separation anxiety or fear of being abandoned just like how his father gave up on him and his brother for Ian, and how his ex-wife probably left him for her new boyfriend.
I think he's scared that nobody would ever love him for him and that he's always going to be a second priority to everyone in his life. Even last chapter, he asked Ian if he's planning to "give up on him" and was visibly relieved when Ian said he would never do that.
I don't know guys, it's just a theory.


Congratulations on losing your virginity, Ian