Well thats a whole lot more PG then i was thinking.
Ci, maybe you are having so much forced sex that you never really get a chance to get horney? Tell him to kick rocks for a week and see if it comes back. Seriously sounds like your just bored and used to a routine. Sex can get stale fast with the same person if there isnt some time apart. Also try doing it in the woods, or in public if your into that.