I think that sangwoo in a way does feel some sort of feelings which could be assumed to be sangwoos version of love but obviously I wouldn't call it that because he does care about bum but he's just crazy and really fucked up and also a sociopath so obviously he can't really show or even feel those properly and bum has had very little love shown to him throughout his life so since sangwoo is at times caring of him he feels strong love towards him and he takes any amount of shit from him to get those small moments which is obviously crazy but bum is also very messed up so yeah
I think that sangwoo in a way does feel some sort of feelings which could be assumed to be sangwoos version of love but obviously I wouldn't call it that because he does care about bum but he's just crazy and really fucked up and also a sociopath so obviously he can't really show or even feel those properly and bum has had very little love shown to him throughout his life so since sangwoo is at times caring of him he feels strong love towards him and he takes any amount of shit from him to get those small moments which is obviously crazy but bum is also very messed up so yeah