As more Americans delay or forego the benefits of marriage, one social scientist is suggesting that young adults’ reluctance to tie the knot may stem from faulty market mechanisms in the “sexual economy.”

At a recent presentation at The Heritage Foundation, Mark Regnerus discussed the concept of sexual economics and his recent book Premarital Sex in America: How Young Americans Meet, Mate, and Think About Marrying, also mentioned this week in The Washington Times.

The dynamics of sexual economics, Regnerus explains, include tradeoffs in the exchange of sexual relationships, in which the “currency” that males offer include commitment, fidelity, and care. In an era of easy hook-ups and cohabitation, less investment is required and the “price” of sex plummets.

But this conceals a host of hidden “costs.”

For example, research has shown that cohabitation has been linked to a bevy of negative outcomes. Compared with their married counterparts, cohabiting couples are more likely to separate and experience infidelity, and they tend to have a lower level of satisfaction with their relationships. In addition, they tend to accumulate less wealth, experience higher levels of depression, and have a greater tendency to abuse alcohol.

Even in subsequent marriages, those who live together beforehand tend to have lower levels of marital satisfaction, dedication, and confidence and are more likely to divorce. And decades of research have revealed the negative consequences of divorce on issues ranging from financial stability to physical and emotional health. Moreover, this “burden of debt” is passed on, as parental divorce has been shown to cast a shadow over the well-being of children and their own prospects for stable marriages in the future.

The negative consequences of premarital sex are not confined to adults. Studies have shown that sexually active teens are more likely to suffer depression and attempt suicide. In fact, in a nationwide survey, the majority of sexually active teens say they wish they had waited longer before they began sexual activity.

In sum, while the price tag on sex may be low in today’s promiscuous culture, the true costs are great—and mounting.