More sex, please

My boyfriend and I are both in our early 20s and only have sex about once every 2-3 WEEKS. We have been together 4 years and work opposite shifts ( I work 8-5 and he works second shift)  but we live together. I want sex more often but he just doesn't want to . He says he is tired when he gets home from work and that I go to bed right after he comes home .. Which is true . He gets home about 10:15 and I go to bed between 10:45-11 to get up at 6a. But even on the weekends he doesn't want to and I don't understand. I honestly don't think he's cheating but I can't help but to suspect. We have a lot of intimate moments other than sex but I still want it ... I just don't understand why every other man wants it all the time and mine just doesn't.. 😞