We do not offer sex as a reward for good behavior like a dog-owner giving a puppy a treat for not peeing on the rug. We are not putting up with sex. We enjoy it just as much as you do, and in some cases, more than you.
We think about sex just as often as you do. Our X-rated daydreams could rival yours, and the stories we relate to our friends would make even the most brazen man blush. Some women want sex less frequently (as do some men), but many women want it often. It's a matter of sex drive, and a low sex drive is not typical of all females any more than a high sex drive is typical of all males.