If you want to have any type of relationship with him, even a friendship you should talk to him and not when the mood strikes him. As him to lunch where you have a time frame, no drinks. Then tell him you like him and would like to see if there is more than just great sex. Stroke the ego a bit he might not know how to talk to you about it or he might not have thought about it. Ask him out to the movies or something non sexual. When he says NO, then ask him what are his feelings toward you other than sex. If he just wants sex tell him while it was good for a while you want more and end it.