Gordon Powers

It's no secret that the number of Canadians choosing to get married has been declining for awhile now. Younger people are marrying less and less, and when they do marry, they're generally older than in generations past.

For centuries, economic security was the reason to pair up this way. Marriage thrived as a practical way to divide labour, harbour resources, have children and arrange for someone to take care of you when you got old.

For a lot of people, that's still the case. And it's probably a good choice. There's lots of research showing that people who are married live longer, are healthier, have a lot more money, and are, well, happier.

What's more, marriage offers legal protection that merging households simply doesn't. But try telling that to the 20-somethings I talk to.

Now, living together as lovers, partners or significant others seems like the more sensible thing to do: Save money by splitting household expenses, maybe manage with one car, get to know each other better and, most importantly, see if you really can share a closet.

Too often though, young adults enter into what they imagine will be low-cost, low-risk living situations only to find themselves unable to get out of them months, even years, later, maintains Meg Jay, a clinical psychologist and author of The Defining Decade: Why Your Twenties Matter — and How to Make the Most of Them Now.

"It's like signing up for a credit card with zero per cent interest. At the end of 12 months, when the interest goes up to 23 per cent, you feel stuck because your balance is too high to pay off," Jay explains.

In behavioural economics, this is called consumer lock-in, the decreased likelihood that you're going to search for, or change to, another option once you've made an investment. Ask anyone with a satellite dish.

The greater the setup costs, the less likely we are to move to another, even better, situation, especially when faced with switching costs, or the time, money and effort it requires to make a change.

And there is certainly a lot of setup costs involved in living together, both emotionally and financially. It's just that they're not that evident until you get there.

"Moving from dating, to sleeping over, to sleeping over a lot, to cohabitation can be a gradual slope, one not marked by rings or ceremonies, or sometimes even a conversation," Jay says. The big problem is that "couples bypass talking about why they want to live together and what it will mean."