FB(fk buddy) question?

i know the rules of having one, but he told me he doesn't want to be just some guy, but that's how it is even if he doesn't want to admit it. Now i'm perfectly fine with pretending he's more than that, (he's using me too) but i don't want to have feelings for him or even care about any of my insecurities or anything else. How can i convince him he's just an FB without getting any feelings for him?