In the comments section of my last post on adultery, a fantastic discussion emerged regarding the sexless . It began with one commenter asking why articles on adultery never mention how happens after in a marriage stops. Several other commenters agreed. Others went further, arguing that refusal to have sex within a marriage—not once in a while but persistently—is as much of a betrayal than adultery itself, if not worse.

This discussion raises two important issues that I want to address:

Is an ongoing refusal to have sex with your spouse a betrayal similar to adultery? Does a persistent absence of sex within a marriage excuse or justify going outside the marriage to get it?

I’ll tackle the first question below and the second in a follow-up post.

There are several things I want to clarify before we begin:

Although I will sometimes use the term “sexless marriage," the discussion applies to any long-term relationship in which the partners expect exclusivity.

I am aware that adultery is not always about sex, and often occurs while there is still sex in the primary relationship. But in this post, I’m specifically talking about adultery motivated by sexual dissatisfaction in one's relationship.

I’m assuming that this sexual dissatisfaction starts some time into the relationship, after an initial period during which both partners were generally satisfied with their sex life (and which generates the feelings of disappointment or betrayal when it ends).

There are many articles about marriages in which both people lose interest in sex (at least with each other), and many discussing what a frustrated partner can do to renew his or her partner’s interest in sex. But there are not many that discuss the of one spouse refusing to have sex with the other on an ongoing basis. This is unfortunate but understandable—I was hesitant to discuss it myself, but the issue obviously strikes a nerve and merits some discussion.

Why the hesitation? We are wary in modern society of suggesting that anyone should be expected to have sex with another person, including his or her partner. Most of us today believe that sexual activity should be completely voluntary, and we fight hard to protect people from coerced sex, whether it's in the form of physical assault or threats related to employment or blackmail. For this reason, most people are very reluctant to suggest that partners “owe” each other sex, either in general or on any specific occasion.

Let’s set that aside for a bit, and instead ask: If there were such a duty to have sex in a relationship, how would this relate to the duty of fidelity (or duty not to cheat)? Most wedding vows—indeed, most understandings of committed relationships, in general—involve a promise of fidelity, usually understood to encompass sexual relations at the very least, but often including any type of external romantic entanglements. Partners are expected to abstain from sexual or romantic activity outside of the relationship, but does this imply that they are entitled to it inside the relationship?

That’s the crux of the matter: It seems natural to say that if one partner promises not to seek something outside the relationship, then he or she has a right to expect it within the relationship. But in ethics, we make a distinction—albeit a somewhat controversial one—between duties of inaction and duties of action. We feel more comfortable saying that someone should abstain from doing something rather than saying they should do something.

For instance, we say that you must never push a child into a lake, but we sometimes stop short of saying that you’re required to dive in to pull one out, although you would be strongly encouraged to do so! Traditional wedding vows reflect this: They are specific as far as what spouses must not do (“forsaking all others”) but vaguer on what spouses must do (“love and cherish”). It’s much easier to tell a person not to have sex with other people than to tell that person that he or she must have sex with the partner—especially given the strong sense of autonomy we grant to sexual activity.

But maybe it’s not just sex. Are we willing to enforce any duties within marriage? Very few people today—outside of certain communities that enforce strict traditional marriage—will assert that anyone “has to” cook, clean, or take care of children for his or her spouse. (Admittedly, it has traditionally been the female partner who has been expected to do these things, which is, appropriately, widely repudiated today.) In fact, the only duty we seem willing to enforce on married people is a specific and negative one—the duty of fidelity. Partners have no duties toward each other than to abstain from forbidden activity with other people.

But this poses a conflict. Consider the following three statements:

People in relationships have sexual needs. They are restricted from satisfying those needs outside of their relationship. Their partners have no obligation to satisfy these needs for them within the relationship.

These three statements are mutually inconsistent, and one of them has to break. Perhaps the one we expect to break most often is #2, in which the frustrated partner does go outside the relationship for satisfaction. I would imagine #1 also breaks, in the sense that the frustrated partner may suppress or deny his or her own needs. This may seem like the noble solution, putting the relationship and the partner above one’s own needs, but it reduces the concept of a sincere need to a mere desire or wish. Some people may find this easier to do than others, but this doesn’t mean they should have to—and some that try but fail end up breaking #2 instead.

Of course, #3 is the third rail in this situation, the one we are hesitant to question. Nonetheless, if one partner voluntarily enters into a committed relationship knowing that the other partner has certain needs—needs that, according to the terms of their relationship, cannot be satisfied elsewhere—doesn’t this imply some level of obligation or responsibility to either satisfy those needs or allow them to be satisfied by someone else? It’s this sense of an obligation that leads some people to say that a refusal of sex is a betrayal on the same scale as adultery.

This leads us into the second question: Does an absence of sex in a relationship justify adultery? If partners do have such an obligation to each other, does a failure to meet this obligation make it OK to have this need met elsewhere? That’s the topic I’ll take up in my next post.

For a select list of my previous Psychology Today posts on adultery, relationships, self-loathing, and other topics, see here.