Why do this guy always stare at me?

Thats because he thinks your pretty and like you but maybe he is afraid to tell you. Or maybe he's thinking he isnt your type so he didnt bother to say anything. Guys usually tend to feel intimidated by pretty girls who they think are out of their lead so they never approach them....Could also be he want you to make the first attempt. Trust me a guy wouldnt stare at you if he wasnt attracted to you.