Why loving someone so hard?

I met a guy on facebook we had long chat also we exchange cell numbers, we talked long hours on phone. We know each other since last one month. We didn't even meet coz we live in two different countries. (Why the hell we human created countries) At a time he seem too busy in his studies. (busy boy). I love this guy so much I keep on thinking about him all the time. (most handsome and lovable personality) Yes, he knows that I love him but he don't know how much I love him. I feel restless also in fear of losing him. Why is so hard to love someone? I can't even concentrate on my studies and work. HELP ME PLZ.