~I need relationship help~?

I've been in a long distance (spare the lectures, please) relationship for a month. People always say one person likes the other more, and in my case, the person whom I am dating likes me much more than I like them. They are already in love with me, but the feeling isn't mutual. They gross me out sometimes--they say things that make my nose scrunch up-- they are annoying, and ask uncomfortable questions. What I need help on: I'm the nicest person you'll meet, and I can't be mean to anyone. How to I let them down lightly without flat out telling them, "I don't feel the same way you do"?