What you have to understand is when a guy says that to you, he’s saying you are the most beautiful girl in the world to him. He’s not solely talking about your physical beauty, he’s talking about all the extra little things that make you beautiful. For instance, the way you hold him down when no one else is around, the way he feels comfortable with telling you anything without feeling like he will be judged, the way you understand him like no one else. All those little things vary within relationships so what one guy may like about his girl, another may not, that’s why it’s okay to say you are the most beautiful girl in the world because you are the only girl in the world that causes him that amount of happiness. There are millions of beautiful girls in the world, but he’s expressing to you that you are that special one that he puts over everything.