The truth is, for most couples, one spouse will have a higher interest in sex than the other. As a sex therapist, I put a lot of emphasis on making sure that couples know that this is normal. It wouldn't be possible for two separate human beings to have the exact same sex drive that operates the exact same way, 24 hours a day, 7 days a week, for decades on end. Differences are to be expected. And, hopefully, differences can be understood and welcomed.