because you're weird? I don't know you so well but that would be my guess...
Maybe he isn't really staring at you. Maybe he is lost in thought and staring into space and you just happen to be in his line of sight.
It may be that his hot girlfriend is talking dirty to him on the phone and he needs to look at something we'll say "less exciting" to keep his composure while at work.
You have something on your face.
men think about sex every four seconds work it out
well it could be you thinking he is staring and he is not do you stair back ???/
why dont smile and wink at him next time (:
C'mon - perhaps at your age I was that dense, but I doubt you are. He is lost in thought about you. Yes, even if he has a fiancee.
u just think he is...in fact he thinks its a bit crostophobic....or it.s... B.O
MAY B HE JUST DOESN'T LIKE U BEEN AROUND HIM
HE MAY HAVE AN ERECTION....
HOW DO YOU KNOW?
Maybe you mad sexy? Or he thinks your weird.