In my interpretation, Jinwoo didn't stop loving Candy he was just depressed. As someone already said in the comments, Candy hasn't changed his personality at all since he was a teenager and lives as an artist. Jinwoo has already changed and matured more, He works in an office, which, knowing Asia, must demand a lot from him. A 10-year relationship without any changes and still contributing socially as an adult is quite tiring. Idk I believe that his relationship became a struggle due to the little free time he had, and as a result he was always tired simply wishing for a break from everything.
In my interpretation, Jinwoo didn't stop loving Candy he was just depressed.
As someone already said in the comments, Candy hasn't changed his personality at all since he was a teenager and lives as an artist. Jinwoo has already changed and matured more, He works in an office, which, knowing Asia, must demand a lot from him. A 10-year relationship without any changes and still contributing socially as an adult is quite tiring. Idk I believe that his relationship became a struggle due to the little free time he had, and as a result he was always tired simply wishing for a break from everything.