not enough sex

Does anybody else have this problem?
Me and my boyfriend have been together for a year and he barely wants to have sex anymore.. we have it once or twice a week and he's not lovey dovey anymore. He works a lot and he works outside but idk if I should accept his "tired" excuse. I always wanna have sex and it makes me insecure when he turns me down. What do I do or how should I feel?