Sex drive

My sex drive isn’t as high as my boyfriends. I could probably have sex one every two weeks and be completely fine with it. Him on the other hand is always ready and prepared every chance he gets. He does get a little upset when I don’t want to and that is fair because we don’t usually have alone time, as we’re always with family. I really don’t know what to do. I don’t want to give him bad sex especially if i’m not in the mood. But I also don’t think the way he reacts to not being able to have sex is okay. He gets very quiet and one-worded. He says it is not fair to him because we never get our alone opportunities and when we do im not down to have sex. But I think it is unfair for me to have sex even if i’m not in the mood. I also think it’s unfair for him to get frustrated at me even when it’s not my fault. Please help guys