Traditional marriage has been in decline over the decades—baby-boomers held a marriage rate of 91%, which fell to 82% for generation X and now hovers around 70% for millennials. An Urban Institute study suggests that a growing number of millennials will remain unmarried through age 40. A Gallup pole states 59% of millennials are unmarried, and a Pew report suggests 25% of millennials are likely to never be married. Why drop in vows?

1. Divorce

It’s not so much the fear of eventual divorce—in fact, Business Insider points out that those millennials who do get married have a lower divorce rate than their parents due to preliminary cohabitation—it’s the effect that their gen x parents’ divorce had on them. In a piece outlining divorce stats, the McKinley Irvin Family Law firm points out that half of all American children will witness the breakup of a parent's marriage.

Of these children, close to half will also witness a parent’s second divorce. With the general divorce rate consistently hovered at 50%, Ming Cui and Frank Fincham of Florida State University assessed the effect of parental divorce on the romantic decisions of their children later in life. They found that children with divorced parents have a less positive attitude towards marriage.

2. Career Goals

More than 75% of high school graduates move on to seek higher education—as opposed to starting a family—suggesting that career and financial stability goals trump marriage. In a Washington Post opinion piece, Catherine Rampell points out that many millennials do not feel they have the economic foundation needed for marriage.

Forbes reports that the average educated millennial is having trouble in the job market, so those able to forge a career will tend to hold it as a priority. But at what point does a millennial feel he or she is economically stable enough to pursue marriage when their career trajectory requires an increasing amount of singular focus?

3. Cultural Shift

There’s been a paradigm shift in today’s thinking about marriage. According to a 2014 NPR piece, 53% of women over 18 identified as single. The notion that marriage is necessary for a woman’s success has shifted drastically with the advent of women’s rights in the 70s and the more recent conversation of reproductive rights.

As the fear of unwanted pregnancy and the stigma against unwed women decline, a sex-positive Hookup Culture has emerged, exploding the speed-dating industry and paving the way for multimillion dollar platforms such as OKCupid and J Date. It’s wholly socially acceptable for millennials to have sex or even cohabitate—and have children—with no intention of marriage.

To keep partnerships alive despite cultural shifts, some are attempting partnership options better suited for the millennials. Psychology Today’s Susan Pease Gadouas suggests “short-term trial union for younger couples, a child-rearing marriage for those who’d like to be nothing more than co-parents, or a socially acceptable live apart arrangement.”

Something called a beta-marriage is offered by Time Magazine, and in 2011, Mexico City considered two-year renewable marriage licenses. So as the times-a-change, the minds-a-change, but the concept of two people working together to support each other and a family still stands firm. Bentley University’s Dean of Arts and Sciences Daniel Everett affirms that biological, economic and social needs will always require some form of long-term partnerships.