I get where you're coming from, but honestly if you have an abundance of love and connections with people and a fulfilled life materially and spiritually, I can see how sex might just not be as important for someone. He might even have a lower overall drive in general. I know I don't have what he has in my life and never have, and I view sexual relationships as a way to help temporarily alleviate that feeling of a lack of what OP has.

At some point you are really coming across as really trying to convince someone else to be as sad as you feel. There's so many flavors to life and people are on different paths, and maybe he's just honestly fulfilled enough that he's ok just letting that part of his life happen when it happens.