I need some Relationship Advice?

My boyfriend and I have been together for some time and we love eachother. We want to get married and have kids and move out of the country next year. He thinks that I think he's ugly and that his friends are better looking then him. He also thinks I don't enjoy sex and that I only keep him around for the emotional part. He thinks I'm going to get bored and cheat on him or leave him. Which is not the case at all! For one I don't care about looks and he's super cute and sometimes I find him extreamely sexy :) There's no way I could ever not find him attractive. He says he knows that I love him and he completely think that I want to change the way he looks and that if I could I would. I just don't know what to do in order for him to believe me. He thinks I don't enjoy sex. I do and he says he knows that I don't. Even if we didn't have sex I wouldn't leave him but i feel like I have to have sex with him because if I don't he thinks I'm going to go looking for it somewhere else. I love him and I'll never ever leave him but I want to know how to fix this problem so we can be happy and move with our life together.