With the limited information you have given, it's difficult to offer advice. How is your relationship functioning with the partner you feel disconnected from? I understand that you care for him, but how would you describe spending time with him right now? Do you enjoy talking to him? Are you happy to see him when he comes home? Do you enjoy being affectionate with him if it's not sexual? If these answers are nos, and you don't know why, it may be that you need to put some conscious effort into reconnecting on more than one level.
Sometimes it's ok to have sex with a partner not because you're dying to do it, but because you want to reconnect and get back into the habit of doing so. Take things slowly and relax into it. Focus on how you want to make your partner feel out of your love for them. Don't pressure yourself to feel or create fireworks, just decide that you want to resume your sex life and take steps to do so, even if it's not on the top of the list of things you'd like to do at that moment.