How to make my dad accept my relationship?

I'm 15 and my boyfriend is 17. When I first told my dad I had a boyfriend who was 17 he didn't care, but now that he has met my boyfriend he is acting like it's the end of the world. My boyfriend is white (Italian) and he was born in Italy and lived there until last year but he speaks English very well and I don't think his nationality is important, but my dad keeps telling me I should find a nice black boy and that because he is Italian he is going to be abusive and that he won't get past the language barrier. I hate when he says negative things about my boyfriend but he won't listen. When my boyfriend met my dad he was VERY respectful and nice and he didn't do anything wrong, but as soon as my dad saw him he didn't like him. I don't know what to do because I really like Nic, but my dad keeps being very rude to him, while Niks family is super nice to me and I don't think it's fair to him to have to put up with my dad. He says he doesn't mind, but you can tell in his eyes that he is upset.