Conflicting sex drives

My boyfriend's sex drive is a lot higher than mine these days. We both used to have really high sex drives but mine went down quite a bit. I don't feel the urge to have sex so frequently anymore. I am fine with once or twice a week. But he has been irritated with it lately because he doesn't think we have enough sex. It really hurts my feelings because I don't understand how it's not enough. I no longer feel like it's necessary to have so much sex. I'd rather it happen once a week or so and enjoy it while it happens instead of losing the appreciation for it. I don't really know what to do or how to communicate about the issue with him. Advice?