15 years is not a short time, your best friend Yook Seongji began to change

He who used to be cheerful and laughed non-stop when he saw you experiencing misfortune

lately he just keeps quiet when he sees you, he doesn't even want to laugh at all and seems to be keeping a secret

Seongji: "oh..."

He just replies to the conversation briefly, his eyes don't show the slightest interest when chatting with you