I was in relationship before and I didn't want to have sex because I felt he didn't care about my feelings. We never really talked anymore. Maybe he wants to feel you care about him and not just the sex. Perhaps do something nice together, talk to him, ask about his day, how his family is doing etc. Don't do it because you want sex but because you want to fill his need for this emotion. Maybe I am wrong and this is not what he is looking for. Maybe ask him say something like "I love you, and want to make you happy. Are your needs being met? what can I do to meet your needs" I hope something I said will be of help. Good luck!