Responses
Hmm maybe this one
http://www.mangago.me/read-manga/forever_mine/?xEdh
There is something like a "curse" that bonds the boy and the girl so the boy must "obey" her otherwise he gets slight punishments
This one too maybe
http://www.mangago.me/read-manga/secret_alliance/?9wZ6
Not childhood friends but they meet at her part time job and he tries to help her overcome her phobia

Can someone recommend me some romance manga where the ML stays with a girl out of guilt (like a childhood best friend who has no family ) but he loves the FL (づ ̄ ³ ̄)づ