Feeling aggravated

My and my bf have been together 4 years. We use to have sex all the time after a couple months of being together. Having sex is absolutely not the main factor in our relationship so don't get me wrong but there's some nights I come home exhausted from work and want to have sex with my bf. Sometimes I feel as if he's not interested. He will be laying in the bed at night before he goes to work (he works night shift) and I'll come cuddle up next to him and try and get him in the mood and it just doesn't happen. He gets hard and still doesn't do anything! I don't expect him to jump my bones all the time but I do like to feel wanted. I know for a fact there's no cheating because I know this man is head over hills for me and does anything and everything for me. I just don't know what to do? It hurts my feelings.