Q&A: My Husband and I Have Opposite Sex Drives
ANSWER: The difficulty you describe is a very common one. In fact, it is the single most common complaint seen by sex therapists.
Few people, let alone couples, have perfectly-matched sex drives. Just as we all have different appetites when it comes to food, the same goes with sex. In addition, sex drive is not a completely stable thing; even the hungriest person will go through times when he or she is less interested. Many men and women also find that their sex drive increases or decreases at various stages in their lives, such as menopause. This is completely normal and only becomes a problem when you and your partner's desire levels are mismatched. If both of you wanted to have sex 10 times every day -- or only once a year, for that matter -- then there would be no problem.
What I will say is that sometimes couples are not as far apart in their desire as they might imagine. Many couples come to a sort of impasse where one partner feels like they have to proposition the other several times a day because they're usually refused; the other partner, in turn, feels like they have to refuse, because if they didn't, they would be having sex 20 times a day!