Retrded ejaculation?

my partner has situational retarded ejacualtion, whereby he cannot with me in the room (i have to stand behind the door). Apparanlty it's the 3rd most common problem in men (after erectile dysfunction and premature ejaculation). He won;t even try to do it with me in the room, he just says 'i know what works and what deosnt'. We.ve been together for wel over a year now, so it can't just be nerves around me. Does anyone know anything about this or what can be done?