Cinderella marries Prince Charming. Aladdin weds Princess Jasmine. In 50 Shades of Grey, Ana falls for Christian. From bedtime stories to films, we are exposed to a repeated idea: that love, or at least lust, crosses class lines. In fiction, cross-class relationships either end in marriage and happily-ever-after, or else in dissolution and even death. But what happens in real life?

Last year, I set out to answer this question by interviewing college-educated men and women who had married partners from different class backgrounds, for my book The Power of the Past: Understanding Cross-Class Marriages. Not surprisingly, their relationships had little in common with the romances we see in the movies. Class had shaped each spouse so much that the people I interviewed had more in common with strangers.

Most of the time, couples’ recognition of their different pasts was acknowledged in little more than a comment about their father’s job or a lavish family vacation. Few people I spoke to reported having parents who plotted against their children’s relationships, or felt they were subject to social stigma for their cross-class relationship.

In fact, it’s usually not until meeting their in-laws that the couples themselves tend to become aware of their differences: More privileged partners spoke of the shock of walking into a house with hundreds of crystal figurines or trying to eat spam with a smile. Less privileged partners told stories of mistaking a “night sail” for a “night sale,” puzzling over how to use a dishwasher, and taking note that their in-laws prefer the theater to the rodeo.

Most couples maintained that their class differences were behind them after marriage, as they now shared a bank account, a home, and a life. Yet, by analyzing how individuals talked about themselves, their partners, and their marriages, I discovered that this was far from the truth. Class had shaped each spouse so much that the people I interviewed had more in common with strangers who shared their class background than with their husbands and wives.

How could this be? It’s because class isn’t only about what you have. It’s also about how the amount of money and material things we used to have shape the type of people we become.

People who grew up in households without much money, predictability, or power learn strategies to deal with the unexpected events that crop up in their lives. Often, these strategies are variations of going with the flow and taking things as they come. Sometimes there’s no other option.

Isabelle, for example, is the daughter of a farmer and a bartender. (All the survey participants have been given pseudonyms.) Her family did not know how much money each year’s crops or tips would bring in. They did not know when a debt collector would call. Thinking about money could not change the fact that it came in unpredictably and that sometimes there wasn’t enough. With little she could do to change the situation, Isabelle learned to go with the flow. She would not think too much about money, but spend as she needed to get by.

People who grew up with parents who had more money, job security, and power grow up with more stable lives. In these conditions, they learn that managing their resources makes sense—both because their lives are predictable enough that they can plan and because their resources are plentiful enough that they can make meaningful choices. Spouses with middle-class backgrounds wanted to manage their resources by planning.

Leslie, another woman who participated in the study, grew up the daughter of a manager. Her family had enough money and power that they had options. They could decide whether to spend money to go on a vacation or to invest in private school. Either way, their plan could be carried through.

This difference—taking a hands-off approach or a hands-on one—followed individuals from their pasts and into their marriages.

It shaped nearly every aspect of their adult lives. In regards to money, work, housework, leisure, time, parenting, and emotions, people with working-class roots wanted to go with the flow and see what happened, while their spouses with middle-class backgrounds wanted to manage their resources by planning, monitoring, and organizing.

The couples had a lot to negotiate. Should money be spent according to gut feeling or only as the carefully-created budget allowed? Should careers unfold as they may, or should specific career trajectories be planned and sought out? Should emotions be expressed as they are felt, or only after they have been carefully considered and an appropriate response has been formulated? Should kids be nurtured but let to grow, or should goals and schedules be set for them?

One couple I talked to experienced these differences profoundly. Vicki grew up as the daughter of an upper-level manager while her husband John grew up the son of two factory workers. Vicki budgeted their money, making sure to save for their children’s college expenses and retirement. John thought their kids could figure out how to pay for college when they were older. People with working-class roots wanted to go with the flow and see what happened would figure out how to retire in the years to come. Vicki, a teacher, plotted how to become a superintendent. John, a restaurant manager, kept his eyes open for opportunities but did not plot how to get from one job to another.

Vicki also had her children’s lives planned before they were born—they would be good students and involved in many extra-curricular activities. John believed he should meet his kids before deciding on how to parent them and that it was not his place to decide who they should become. Vicki summed up their differences describing her own style as, “We need to plan! We need to schedule! We need to be neurotic!” and saying of John, “For him, it’s ‘It will always work out. It will always get done. Don’t worry.’”

Most of the couples I spoke with found ways to work out these differences, and their lives were much more mundane than a movie would dramatize. But despite years of marriage, two usually did not become one; marriage did not magically transform the less privileged partner into a person who easily fit into their new class.

As a result, some people who “married up” felt continually uncomfortable in their new class, though people who “married down” tended to feel more at ease around their in-laws. Nevertheless, the movies do get some things right. Despite the constant negotiations that living in a cross-class marriage entails, love can cross class lines and couples can live a real-life version of happily-ever-after. Many of the couples I interviewed had been together over half of their lives, and all signs suggested they would be together for many years to come.