Bah, you should stop the friends with privledges thing if anything. Just because you guys are making out only makes things more complicated. It means that he is having his cake and eating it too, while you are driving yourself mad by thinking/wondering about what he really feels.
When you make out or have sex with someone, females produce a chemical called oxytocin. This is the same chemical that one produces while pregnant, and then again after giving birth. It is the chemical/hormone produced that helps females "bond" easier. Guys produce this chemical too, just not as much as females. That is how a guy can do the friendship with "privledges" thing and control his feelings where it will be much harder for a female to do the same thing without producing some type of feeling towards bonding and attachment(even if there is no real commitment she will feel that there is, even if she denies it).
I was in a relationship like this for 4 years and it didnt get me anywhere! Finally I got tired of it, and over his ass, and found someone that is willing to commit to me. He is my best friend, my lover, my soulmate.
You should wrap up a big bottle of lotion, put a big pretty bow on it and hand it to him for a late birthday pressent, then tell him to privledge himself. Then go find yourself someone that is willing to treat you like you should be treated.
Oh here is a link about oxytocin: link removed