Most men feel quite insecure about their penis. And your bf knowing that your not a of fan of his genitals and that you don't wish for him to give you an orgasm might be very hard for him to understand. Especially as in todays society sex and pleasing your partner in bed is all magazins and tv talk about, it's perceived to be normal for a woman to crave orgasms etc. Your bf may feel that it's him that isn't sexually attractive to you. Maybe some couples counseling would help you both