Friends With Benefits? That Makes No Sense.

"Friends with benefits" is a concept that I can't fathom as an aspie or even just as a human being.  (I guess I don't need to just be an aspie not to understand.)  How can someone have sex with someone who is just a friend.  Wouldn't there have to be something there for them to have sex?  I understand it's probably lust or just the burning desire to have it.

Everyone has that, but when you're doing it the other person is seeing you bare, not physically, but emotionally and everything.  They're seeing you almost as a whole.  There is a lot more to sex than just mechanical and biological desires.  You're putting everything out on the line when you're having sex for the first time.  You're showing and giving your all to someone.  

Why do I see it this way?  Why not?  I can barely handle a hug from some people, especially from someone I barely know.  I feel uncomfortable with physical affections like hugs or kisses.  So that's the aspie part of me. Aspies, we have a hard time with connections to people.  That's why this concept of "sex without emotion or little emotion" doesn't seem to make sense to me.  I would have to be terribly comfortable with someone to do that with someone.  That's why sex isn't all "I'm horny, so I've got to do something about it."  I get desires like anyone else, but it doesn't make sense to do this without knowing what you're getting into.  The questions you'd have to ask are "How is this going to affect the relationship I'm in?"  "How will this make me feel?"  "How will this make my partner feel?"  "Will it break things?"  "Will it make things?"  "How do I feel?"