Locking lips and interlocking fingers are harmless enough, but locking into love is seductively dangerous—both figuratively and literally. Twenty-first-century lovers have become so captivated by the metaphor that, in 2015, the pont des arts in Paris had to be released from the crushing weight of forty-five tons of padlocks that lovers had secured to it. Keys, tossed over the rails, litter the Seine. While the Parisian love locks were auctioned to raise money for charities, padlocks still smother memorials around the world—from other bridges in Paris, to the Brooklyn Bridge, to fences in Hawaii and Australia. Urban planners have now become accidental heroes in the crusade against the obsession, although the phenomenon persists despite their best efforts to thwart it.

On a Valentine’s Day that comes hot on the heels of #MeToo, it’s worth reflecting on some of our rituals and symbols of love. For example, while I hope chastity belts are a relic of the past, ironmongery such as wedding bands are still among our ultimate signifiers of commitment—perhaps even more so than the marriage certificate that binds us legally. In some ways, this makes sense. Steely icons are strong, stable, and durable. Metallic tokens outlive us to such an extent that they remind us of the possibility of everlasting love. Most of us want love, and we want it to stay, so no wonder we’re tempted to fetter it in chains. However, these exalted symbols are deeply troubling in other ways. Not only are they cold and hard and inflexible, but they’re also relics of a long tradition of possessiveness: wedding rings are a vestige of dowry traditions and signify being owned.

Friedrich Nietzsche might have been disappointed, but not surprised, to learn that we’re still obsessed with locks to symbolize love. Love, he thought, can be “the most angelic instinct” and “the greatest stimulus of life.” But too frequently, love manifests as a greedy and decadent desire for possession. As Nietzsche postulated, lovers all too often act like “the dragon guarding his golden hoard” and treat a beloved like an exotic bird—“as something also which must be cooped up to prevent it flying away.” Chains can be comforting, like lovers’ arms, but Nietzsche was an advocate for freeing ourselves from these petty shackles of romantic mythology, particularly the ideal of securing love. Love is a feeling, and it’s absurd to think—let alone vow—that we will feel a certain way till death do us part.

Jean-Paul Sartre, who read (and ruthlessly mocked) Nietzsche in college, spent most of his time drinking aperitifs in Saint-Germain-des-Prés cafés just steps from the pont des arts, scribbling in notebooks, and pursuing young, beautiful women. As a champion of existential freedom, Sartre argued that to accept other people’s view about how you should live involved a kind of self-deception that he labeled bad faith. No friend of bourgeois norms, he argued that each of us is responsible for our own life choices. A free individual shouldn’t lock him- or herself down in a relationship that may grow to be an uncomfortable cage. Throw away the key, and you throw away your freedom. To be free is to have the possibility to change course, redefine yourself, and overturn others’ images of what you should be.

According to Sartre, love exists only in its actions. So if buying a brass lock and leaving it, along with thousands of others, to weigh down a monument is for you a special, beautiful, and meaningful act of love, Sartre probably wouldn’t have stopped you. However, he would have been dubious about the authenticity of such a gesture. The love lock is not an ancient tradition but a fad that started in Rome in 2006 after the popularity of the book (and subsequent film) I Want You, by Federico Moccia. In the story, two lovers lock a chain around a lamppost on the Ponte Milvio in Rome and throw the key into the Tiber. It symbolized the idea that they would always belong to one another.

The symbol of a lock may seem completely inimical to an existential view of love. Once the key has been thrown away, there is no exit. Yet Sartre used the same metaphor differently, suggesting that lovers could act not as a lock but as a key to unlocking your inner being. Without someone scrutinizing, engaging with, and appreciating you, there may be aspects of yourself that will remain forever invisible. A lover’s intimacy can reveal those desires and attitudes.

For Sartre, the joy of love is when we feel secure in our possession of one another and find the meaning of our lives in and through the other person. The problem is that this is just an illusion. There is nothing at all secure about romantic love. Since lovers are free to choose to be in a relationship, they are also free to leave, and this makes love perpetually vulnerable. According to Sartre, this drives lovers into vicious circles of sadomasochistic power games. They try to control each other and demand the sort of possession that the padlock implies. The outcome is that lovers end up attempting to rob each other of their freedom without ever fully achieving the possession they lust after, which is why Sartre concludes that love is conflict.

There is nothing wrong with hoping that love will last. In fact, the hope that it will endure differentiates romance from lust. For Sartre, lovers define themselves by choosing to love each other both now and in the future. Yet that is the paradox of love: we can’t know what we will be like in the future, and as much as we can freely choose to commit to it, to tie down a future self is its own denial of freedom.

One might wonder: Can’t we just let go of the desire to be one another’s ball and chain? Simone de Beauvoir certainly wondered about it and argued that the best relationships are authentic. In authentic relationships, lovers respect one another’s freedom and keep exercising their own. Beauvoir and Sartre had an open relationship, a radical departure from the conventions of the time. Still, they demanded an assurance that they were each other’s primary partner, which may have denied them certain other freedoms.

Possessiveness is so fundamental to the experience of love, Sartre thought, that to overcome the desire to possess a lover might be to overcome love itself. And yet in many ways, he advocated less for the padlock and more for the key: Love is like hurling yourself off the bridge into the Seine. It requires courage to jump into a relationship, and you do not know where and when you will settle, if at all. Sartre did it anyway—and would have recommended that we do too.

Skye C. Cleary is the author of Existentialism and Romantic Love and teaches at Columbia University, Barnard College, and the City College of New York.