Most Helpful Guy
Cause he likes you and you let him. You are sending him wrong signals by playing his game. Unless you like it. Then why complain?
Most Helpful Girl
Tell him to stop.
He sees you talking to him as something more.
& you letting him in only shows him that you accept his behavior allowing him to continue to pursue you.
If you feel uncomfortable, ask him why he's doing this and tell him to stop.. or better yet leave him...
He sounds creepy.