Friends Suddenly Turned Against Me?

Well, today at school my friends were acting really nasty against me and were spreading things that wernt true. And at lunchtime 2 of them said to my boyfriend hows me and this other lad getting on. Well my bf believed them and that i had been chatting up another guy which wernt true but then my boyfriend believed me and said i wouldnt do a thing like it which i wouldnt. My 'friends' have been real bitches today. They dont like my boyfriend but me and him have been together a year now so whats their problem? Im 14