Side chick ?

Okay here is the thing, me and my boyfriend have been dating for almost 3 months. And before we started dating I acknowledged the fact that he has female friends but the problem is: what happens when they are more important than you are? Don't get me wrong yes he pays attention to me and says he loves me but I don't feel like his girlfriend more like a trophy. He had this one friend ( female ) who he is constantly texting and Snapchatting and he never lets me read the messages between him and her. He texts her more than he texts me and she is constantly brought up in all our conversations. He feels like he isn't doing anything wrong and I'm giving him the benefit of the doubt . I don't want to break up with him because I honestly do care for him ... What should I do ?