What should I dooo? Helpp?

I've been dating this guys for 8 months, He's 18 I'm 15. I lost my virginity to him. And he tells me he is so happy with me and that's he loves me constantly he takes me to dinner and stuff and he always cares about me and he always watches out for me, but the problem is the feeling isn't mutual. I don't know why I don't have feelings for him. I feel bad because I try to like him but I just can't. What should I do?