Is there something wrong with me?

So I've been dating this guy for about 4 months now, we are in a serious committed relationship and in the beginning things were amazing in bed , we had sex all the time ! And he really seemed to enjoy it and get into it . Now we hardly have sex and it's hard for me to get him to have sex or even let me give him oral, I've talked to him about it and he said that it's not me , it's not my fault and that he just doesn't feel sexually driven , but he was an ANIMAL before , so I'm upset and confused .. Is it something wrong with me ? :(