Well, I can't say you're the first person I heard this from, but I really don't know much on any advice... Yet, for clarity, it is quite natural for anyone to be attracted to the person they first had sex with... EVEN WITH GENETIC MATERIAL lol :) Yet, back to the point, you can say that this is too far, and begin more masturbation. Yet, then again, you can talk with him to say we need to be in seperate lives, yet not like " Never get to see that fine ass again! ", just try this, more talking with him, more masturbation for you, to explore options, and lessen the sex with him... This can bring you two close without the " Happy Happy, Horizontal monster-mash " Occuring lol :) I wish you luck!! <3
Sincerly,
a douche bag Xj