My boyfriends style sucks?

okay well ive been with him for 5 months and im a big prep. but i also shop at target kohls and stuff but not for main pieces. well my bf refuses to wear n e thing prep. hee only shops at kohls, but somehow he picks up the ugliest stuff he wears red bball shorts and a DIFFERENT colored red shirt and ill tell him he doesnt match and hes like eh whatever. and i put in effort to look good for myself for him and for an image. i really love him and attraction is really important in a relationship but im loosing it from him. how should i tell him that?