You want to know, "what should I do to make him horny about this relationship?" You say he doesn't give a shit about you? What are you doing with him to make him not care? Why do you give a shit about him?
If the issue is sex and desire for you, maybe you are really not his type. Maybe you are putting too much pressure on him. You don't give us very much to go on here!
In general, in my experience, it doesn't take much to make a guy, virtually any guy, horny. So, my advice is find another boyfriend who doesn't take as much work and will "give a shit!"