If he tells her that, she will run away on the first chance. He can't even show it to her. This person hates him the most. There are billions of people in the world. He doesn't understand why does it have to be a crazy person like her. Honestly, he has never been in love before. He has never even dated before. Then, she is his first love?
He doesn't know how it is supposed to be. How he should treat her or how he should make her love him back? Whatever he does, she dislikes him more. It's only the beginning.