In her raw, human account, Courtney Sender struggles to find an answer to a riddle many in my generation face: If I consented to casual sex, why do I feel abandoned when my partner leaves?

There is a ghost in the room when millennials have sex. Connected by apps and delivered by rideshares, modern lovers are haunted by the knowledge that even a 99 percent match or a super-like can disappear in the morning, leaving nothing but a first name.

Writing in the New York Times, Courtney Sender describes wrestling with feelings of abandonment after such an encounter when her partner ghosted her and vanished without explanation. In her raw, human account, Sender struggles to find an answer to a riddle many in my generation face: If I consented to casual sex, why do I feel abandoned when my partner leaves?

The problems with casual sex aren’t new, and they aren’t unique to my much-maligned generation. But where there used to be a shared cultural understanding of romance and heartache, the march of progressive sexual ethics has been so complete that we no longer have the vocabulary to explain what we’re feeling.

When I left the heartland to join a private medical practice outside Washington DC, I began to see just how thorough this transformation has become. In many ways, DC represents the best and worst of my generation. Idealistic, ambitious young men and women from around the country come to work in politics, government, or the ever-nebulous “consulting” industry. They hope to make their mark before they settle down somewhere more humane for the rest of their lives. While they’re here, they do what human beings have always done: reach out to others for intimacy.

Like the jobs that bring them here, however, these romances are often temporary affairs, the health effects of which bring many young professionals to my clinic. Few people I meet really expect to find lasting love in a city that no one calls his hometown.

Mercifully, my profession has become adept at treating the physical consequences of this approach to sex. But the emotional consequences are more difficult to heal. It’s these emotional consequences that Sender describes.

As a younger man, her partner was thoroughly trained in modern, politically correct sex—asking for affirmative consent for every touch, every kiss, every act. This initially seemed odd to her, but she grew to interpret his gentle demeanor as an expression of profound care. Later, she realized this ritual of consent protected only her body, not her heart, and only for that single moment. “Sex felt like a sacred act,” she writes, “and then he disappeared.”

When her roommates scoff at her for this: “A sacred act? Girl, you sure don’t treat it like one,” Sender tries to answer, comparing casual sex to praying with strangers or donating to charity. These metaphors ring hollow. After all, no one cries if strangers from church fail to show up for breakfast the next morning.

Sender is right that sex is sacred, but her analogies break down because there’s a more specific word for the feeling of profound, sacred care for another person that she describes. The natural word for this romantic sentiment—a word Sender cannot bring herself to write even once in this article—is love. Sender rightly perceives this feeling in the transcendence of sexual intimacy, but her language is constrained by a philosophy that believes the connection between sex and love is optional.

For this reason, modern sexual ethics have no answer for why our author should feel betrayed. As long as those involved are “consenting adults,” anything goes. Since there is no inherent meaning in sex, importing deep sentiment is unreasonable or even clingy. In an attempt to justify her feelings, then, Sender has to expand the definition of consent:

[C]onsent doesn’t work if we relegate it exclusively to the sexual realm. Our bodies are only one part of the complex constellation of who we are. To base our culture of consent on the body alone is to expect that caretaking involves only the physical. I wish we could view consent as something that’s less about caution and more about care for the other person, the entire person, both during an encounter and after, when we’re often at our most vulnerable. Because I don’t think many of us would say yes to the question ‘Is it O.K. if I act like I care about you and then disappear?’

While the author makes it clear how special this particular encounter had felt, it wasn’t the first time she was hurt. As she writes: “Sex makes me feel unsafe, not because of the act itself but because my partners so often disappear afterward, whether I waited hours or months before the first time. So it’s after sex when I feel truly vulnerable.”

These critical sentences show it’s not only being ghosted that left Sender feeling so hurt. It’s the fact that her partners left her feeling abandoned after sex. Sender rightly understands that good sex requires you to care for your partner, and she knows caring about your partner means you can’t “just disappear.”

But how long a commitment would be enough for her? A week? A month? A year? Until the author’s feelings have faded? Sender seems not to know. Ultimately, the only alternative to a relationship with abandonment as an acceptable ending is a relationship with a permanent commitment.

The author wants those she couples with to take responsibility for her feelings and stay with her. Yet she’s unable to define what that responsibility means. She wants the assurance of commitment but not the restrictions that must come from making ties that bind. The casual intimacy she seeks is a contradiction in terms. As poet and essayist G.K. Chesterton writes:

If I bet I must be made to pay, or there is no poetry in betting. If I challenge I must be made to fight, or there is no poetry in challenging. If I vow to be faithful I must be cursed when I am unfaithful, or there is no fun in vowing….For the purpose even of the wildest romance results must be real; results must be irrevocable.

There is a ghost in the room when millennials have sex: an intimate bond that no mere words of consent can remove. Our spirits know what our minds can’t admit—that in the interplay of bodies is the exchange of a vow.

Sender’s article is poignant because her incredible honesty betrays this contradiction between her heart and head. Whether her lover asked permission to touch her or not, she knows she has been treated as a consumable and discarded. If modern sexual ethics were correct, this wouldn’t be a dilemma—but for our author and millions of others, it clearly is.