Long distance

My boyfriend and I have a long distance relationship and we are doing really well except for in the bedroom. In person we are both fine and its so great but because we don’t see each other only a week every two to three months. We try to keep the romance alive over the phone when we are apart but lately I just don’t want to get naked for him. I love him and he makes me feel great but I also feel ashamed of myself and that he won’t like what he sees. The romance is dying and he’s getting frustrated and thinks I don’t like him in that way anymore. But thats not the case. And i just don’t know what to do about it. Any advice?