We don't have sex anymore

I can't remember the last time we had sex. We're two cis men and up until a few months ago, everything was fine. Our sex life was great, we were doing it regularly and satisfying each other. We would do it even if we were tired because we wanted each other. Now I feel like I can barely get my partner aroused. It's like he doesn't want to be with me. He's fine spending time with me and he assures me that he loves me, but sex, he's just like "meh". It makes me feel undesired and not sexy. I don't know what to do. We've only been together for a year and a half and we're both young. I feel like maybe it's because we only see each other once a week but we're planning on moving in together in three months so I'm hoping that will make things better but I'm having second thoughts, like, what if he decides he doesn't want to be with me anymore after we move in? I'm scared and worst of all, as sexually frustrated as a closeted virgin. God.