Addcted to my body

Because you psychologically castrated him into becoming a male dyke.Which is a guy with sexual disfunctions incapable of performing correctly the ordinary sexual act,penetrative sex,so he does everything but that.

You wouldn't believe it but the reasons for this could be several.Including:
According to certain mainstream adolescent cultures and customs that way you avoid going to hell,and do not risk to get the her eggo preggo.
So it could just be a case of extreme "pregnancy paranoia".Or maybe he is a premature ejaculator and doesn't wanna disappoint you and make a fool of himself,and he is afraid of you picking on him or joking around about whatever issue he might have.
Or he just found a way to masturbate that satisfies him more than all the sex he could ever have with you so he just goes down on you. Either way it is sort of normal in certain circumstances but since you didn't provide the necessary informations about the conditions in which this particular behavior took place,I can't quite tell you whether it's normal or not.I need more details. Or I'll have to guess till the only word left in my brain will be "Or".Damn.

Why don’t you ask him? It sounds like you’re not satisfied with your sexual relationship and you deserve to be.

He is having sex with you, cunnilingus is a great joy for many normal men and the joy is greater if the desire is higher. Enjoy the fact that he loves to pleasure you and then tell him you want to pleasure him. Taking turns can be great fun.