I am worried about them, and I let them know it. This is not because I think that a couple can’t have a viable relationship without sex—the absence of sexual desire, when it is mutual, is not necessarily an indicator of dissatisfaction. There are a lot of ways to be happily committed, and not all of them include sex. However, if one partner really misses sex and can’t engage the other, a pernicious downward spiral is set in motion.