Inviting people to your wedding can be lots of fun, as it shows the day is quickly approaching and may make the whole thing feel more real. However, it is here where you will have the trickiest waters to navigate in terms of etiquette: who to invite, the question to include a plus one or not, and more. Now that many couples are staying together for several years before tying the knot themselves, your mother’s old etiquette guide may not have sufficient advice.
Plus ones are always a nice gesture for single guests, but it's important to keep in mind that established couples are considered a social unit. While it is not your place to judge how serious a relationship is – after all, some people get engagements after only a few weeks – it's best to have a consistent policy when it comes to duos. As much as you may want to keep the guest list from growing, including all sweethearts is the easiest way to keep from upsetting or offending any of your friends and family.
If the couple lives together:
You must put both guests' names on the invitation, even if you have never met the significant other. It should not be difficult to learn the name before you send out the invitations. If you know both of the people in the relationship, there is no excuse for not including both of their names, despite the fact that you would have only invited one of them if they were not a couple. Your brother's girlfriend probably knows not to go to the wedding if they break up, but that doesn't mean she wouldn't be hurt to be called "and guest" after spending Thanksgiving with your family.
If the couple lives separately:
When a couple does not live together, you should ideally send an invitation to each person, but it has become more acceptable to send it to the primary invited guest; however, you should still include the significant other’s name on the inner envelope of the invitation. However, if you are friends with both and you would invite them each even if they were not a couple or broke up tomorrow, then it's probably best to send them each an invitation to their respective homes.
In the event that you find yourself unable to learn the guest’s name before sending out the invitations, perhaps because your invited guest does not know who they will bring, only then may you write “and guest” on the invitation. But please do your due diligence, and in this case make sure your invitee knows to supply you with the name so you can have a place card for that person. If you're worried about the couple breaking up, well, unfortunately the same possibility could happen with a married couple – but you wouldn't only invite one half of a married couple, right? There is also an additional benefit – besides having good manners – to writing the significant other’s name: If the couple does sadly break up, your invited guest is less likely to turn their plus one into bringing an unvetted rebound date to your wedding.