Why does he lie to me?

Wow that was long...you could really simplify your life by just telling the guy you like him instead of denying it repeatedly. He's just doing the same thing you are. Lying about having a girlfriend to put you on the defensive, the same way you are lying about not liking him to put him on the defensive. Why don't' you guys just try being friends and see if you really do like each other. Forget the "girlfriend/boyfriend" labels. Just BE FRIENDS for now.