Why millennials aren’t moving in together as a trial marriage

For years, moving in with a partner was an almost sacred decision, saved for the latter stages of a relationship when partners were on track for marriage.

Just a few decades ago, many couples didn’t even share a home until they tied the knot.

And while this is still the case for some people today, especially within specific religions or cultures, moving in has become commonplace in countries such as the UK and US – and much less likely to be linked to assumptions about the future. 

New research from the UK provides a close look at young people’s changing behaviors and attitudes towards moving in with a romantic partner for the first time.

As well as confirming younger generations are breaking the mould around past co-habiting patterns, the study’s results also indicate that the way millennials in particular feel about moving in with their first significant other is different than previous generations.

Rather than being a significant milestone on the pathway to permanency, moving in today might be more linked to convenience, says the researchers.

It seems young people are continuing to dislodge old notions of what it means to be with a partner, both now and down the line – and proving that milestone moment don’t look the same as they once did.

No longer a ‘test run’

It’s fitting to look at trends around co-habitation now, since co-habitants are the fastest growing demographic. 

ONS data from 2018 shows the number of co-habiting couples is outpacing married couples and lone-parent families, increasing more than 25% between 2008 and 2018. 

There are similar patterns in the US: millennials are more likely than Gen X were at the same age to be living with a romantic partner.

Pew Research Center data from 2019 showed 12% of millennials were co-habiting and unmarried; at the same age, in 2003, only 8% of Gen Xers were doing so.

Traditional narratives around co-habitation are often directly linked to marriage, whether believing that people bunk up with the explicit intention of settling down, or at least ‘checking’ their long-term compatibility with their partners.

But younger generations may be proving these storylines wrong.

Researchers from University College London and the University of St Andrews examined the changes in views around what it means to move in with a first partner now versus years ago, as well as the strength of those partnerships.

Using data from the British Household Panel Survey and the Understanding Society study, the researchers examined a study sample of 3,233 people from three birth cohorts: 1974 to 1979, 1980 to 1984 and 1985 to 1990, observed between 1991 and 2016. 

The findings showed co-habiting behaviours and relationship outcomes of these groups differed dramatically – even though the groups studied were relatively close in age.

In terms of staying with partners, the group born in the 1970s had a 50-50 chance of staying together.

Data from younger cohorts indicated less long-term stability. When examining how long couples stayed together, 25% to 27% of couples in the two older cohorts separated within two years of moving in together. In the youngest cohort – those born between 1985 and 1990 – this percentage shot up to 43%.

The research also provides a sense of the motivations behind moving in together.

The data indicated that people born in the 1970s mostly treated first-time co-habiting as a test run with partners – a kind of ‘trial marriage’.

Yet millennials seem to be less interested in the ‘try-before-you-buy’ approach, instead choosing moving in as a practical decision.

The study’s lead researcher, Alina Pelikh, a research fellow in demography at UCL, says there are many reasons for this, including convenience and economic benefit as well as less stigma around co-habiting.

Unlike in past generations, the younger groups surveyed split with their first co-habiting partner in much higher numbers (Credit: Getty Images)

This chimes with other data around the acceptability of moving in together. An increasing number of people approve of co-habitation, even for partners who don’t plan to get married.

This is particularly true among younger generations: additional 2019 Pew data showed more than three-quarters of people aged 18 through 29 say it’s acceptable for unmarried couples to live together, whether or not they plan to marry.

Galena Rhoades, research professor in psychology and director of the Family Research Center at the University of Denver, US, agrees that changing social attitudes around co-habiting have enabled younger generations to adopt a more casual attitude around moving in together, rather than viewing it as a test-run for marriage.

“Co-habiting is becoming more and more a stage in dating, rather than a stage in marriage,” says Rhoades.

Her research also shows millennials are less concerned about co-habitation as a path to marriage; often, younger generations report that they just started living together out of happenstance.

“It's not really seeing [co-habitation] as a decision or a commitment event in a relationship. And I think that's become more and more true over time.”

Pelikh suggests young people see living with a partner simply as an alternative to being single, and that marriage or long-term partnership may not even be a consideration for years to come.

She also highlights the speed with which these changes have occurred, saying:

“We see that there is a lot of difference between the youngest ones, those [born] closer to the ’90s, and those closer to the ’70s.”

Usually, she explains, these substantial attitude swings generally occur over generations – say, between the 1950s and 1990s – yet they occurred in relatively short periods of time. She says such dramatic differences among groups only five years apart is surprising, and indicates change happened unusually fast.

Importantly, Pelikh caveats that the data only accounts for partnerships formed up to age 27.

So, we don’t know how first-time co-habiting millennials after this age fare. She posits that these relationships could potentially be stronger, driven by factors such as people knowing themselves better, or being in a more economically stable position.

‘The bigger picture’

While we have a sense of Gen X and millennial trends, what’s not clear is whether Gen Z will continue these behaviours.

Some signs point to Gen Z continuing a more pragmatic approach like millennials.

Indeed, Gen Z are finding themselves in similarly tight economic situations, and some research has shown this generation is increasingly pessimistic about this changing.

Additionally, as positive attitudes toward co-habitation grow, Gen Z will be making decisions about moving in together free of the stigma many of their predecessors faced.

In some cases, Gen Z are also showing signs of prioritizing establishing themselves as individuals before coupling up.

This may continue to push younger generations’ first co-habitations increasingly later in life, similar to patterns the researchers observed in millennials.

Regardless of how these behaviours play out for Gen Z, Pelikh believes these findings are particularly pertinent now, since hitting life milestones is no longer linear for younger generations – yet there’s still a stigma around their transitions not following ‘traditional’ timelines or behaviours.

In other words, it may be helpful to show how common it is for young people to split with their first-time co-habiting partners, to shake loose some of the remaining judgement from older generations.

Pelikh believes this data spotlights “the broader complexity of adulthood” – and can potentially provide a sigh of relief to those who feel nervous about not taking the path once considered standard.

“We all live our lives, but what we don’t have is the bigger picture,” she says.

Research like this helps continue to highlight the dramatic way milestones are morphing among generations.

What may have been meaningful for one generation is quickly changing – and this may paint an increasingly vivid picture of what the future of adulthood looks like.