According to the Bureau of Labor Statistics, more than 50 percent of adults in the United States are single. And yet, as Rebecca Traister points out in her thoughtful and thought-provoking book, "All the Single Ladies," we aren't living in a society that reflects that.

And while that's true of laws governing parental leave and government benefits, it's especially accurate when it comes to the arguably outmoded rules of weddings. Traditionally, a wedding invitee isn't given an additional invitation for a second person unless the couple is married, engaged or has been cohabiting. Some advisers recommend stretching that definition. Martha Stewart suggests making your own call which could include flexibility: "If a couple has been dating less than a year, only the partner you're close to is invited, for example. Or, include the significant other only if one of you has met him or her." The idea here being that you have to establish a "rule" of some kind for plus-one invitations, and you should stick to it across all parties.

There are plenty of single people who would love to attend a fun wedding party — but don't want to do so alone. As the population of singles expands, they have been speaking up for the idea that everyone invited to a wedding should get an invitation, no matter what their relationship status. As you can see from the raucous (and funny!) debate in the video below, from the show "The Real," opinions about this often get split along relationship lines: Those who are in one tend to think plus-ones aren't necessary for single people, but single folks generally argue for bringing a friend or date.

Jessica Gross writes of the absence of plus-one invites for singles:

"In the name of empathy and compassion, and with a nod to current social norms, I hereby declare this tradition preposterous. At weddings and other formal occasions — office holiday parties, your garden-variety banquet — every single adult should be invited with a plus-one. Period. If you have a tight budget, invite fewer people. I'm serious: I would rather not be a fringe-level invitee if it meant every adult could bring a plus-one if she chose."

This system is both fair to everyone (no different rules for different people) and gives single people an option, which makes sense. For those who are comfortable flying solo — or prefer it for events like this, they still can. Depending on who's getting married, I often like going to weddings on my own, and I have a partner of many years. I enjoy talking to the older people at weddings and have no problem sitting at a table by myself during slow dances. But those situations make some people very uncomfortable, and for those who don't want to go it alone, giving them the choice to bring a date or a friend to hang out with is a kindness.

Gross goes on to suggest that insisting on certain types of relationships as somehow sanctioned as wedding date-worthy and others not is a judgmental and outmoded way of thinking. It doesn't take into account the myriad ways people create families in the modern era.

"As women live more of our adult lives unmarried, we become ourselves not necessarily in tandem with a man or within a traditional family structure, but instead alongside other women: our friends," Traister writes in her book. If this is the case, then why shouldn't a wedding guest bring a friend with them?

Of course, if you're throwing a wedding, you get to make the rules about who is invited and who isn't, based on your personal opinions and budget. It's worth keeping in mind the point of a wedding as you suss that out. Don't you want those who attend to have a great time?

Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.

Should every adult get a plus-one to a wedding?
Some singles argue that attending a wedding alone is an unkind expectation.