During my recent trip to London, I was speaking with a colleague while taking afternoon tea at The Wolseley. One question which came up was one of sending invitations for weddings to single (unmarried or otherwise unattached) people. My friend, a social commentator and etiquette expert from Toronto (now living in London) was very clear that she felt that any single guest should be given the opportunity to bring along a guest of her choice to a wedding and that the invitation should always include "and guest".
After mulling this idea over in my head for a while, I decided that I have to disagree with this idea as I feel that this request is not usually a reasonable one. There are any number of factors to consider when constructing a guest list for any event, a wedding being no exception. For one thing, there can be space constraints; there can be budgetary restraints; and there can be legitimate personal preferences, such as not wanting total strangers at what is usually a very private affair. Although I can understand that attending parties and events such as weddings as a single person can feel awkward, it is not the responsibility of the host to accommodate unknown guests as a rule. If the host decides that single guests can bring a friend along, then it will be indicated on the invitation. It would be considered rude to ask to bring a friend to any event where invitations are issued and it would be unacceptable to simply show up with an uninvited guest in tow.
There will occasionally be instances where the host may be unaware of recently established relationships, which would actually make a single invitation awkward or even inappropriate. Generally speaking if a couple sees themselves as "an item", they should receive a joint invitation. If there has been a real oversight made, which can happen quite inadvertently, then it would be acceptable to phone the host and explain the situation immediately upon receiving the invitation. If a relationship emerges after the invitations are sent, but before the event takes place, it is still incorrect to call and ask if you may bring a guest. It's important to remember that weddings can be very expensive affairs, often costing the host well in excess of $100 per guest. If you feel too uncomfortable going out by yourself, you are obliged to regret the invitation or steel your nerves and soldier on.
I have also been asked if it is acceptable to invite one person of an unmarried couple to an event such as a wedding if the other person is unknown or even disliked by the host. Unfortunately this is not acceptable. I'm afraid you have to take the good with the bad.Once a couple becomes a couple, they should be treated as such. It is insulting to do otherwise. My experience has been that most people can pull themselves together and not ruffle too may feathers when attending private functions. If you know that unpleasantness is likely, it is best not to invite them if you are unwilling to cope with whatever may come your way civilly. I am a firm believer of editing guest lists as necessary when friend's lives change and negative energy overtakes them. As host, not only do you have complete control over the guest list, you also have the responsibility of assuring all of your guests have an enjoyable time. Unless you have an agenda which includes potential surprises, my advice is to "avoid the avoidable".
Whenever I am putting together a guest list for myself or for a client, I try to consider single people carefully, being sure to seat them with people they know. I also like for them to have friends at the party with whom they will feel comfortable. Not everyone is an extrovert and for anyone who is somewhat shy or withdrawn, I make a special effort to ensure that they will not feel stranded. It takes special thought and a good deal of time to construct a good guest list. When you receive an invitation, remember that the host has likely given a lot of thought to this matter. If you have not been invited to bring a guest, or your children for that matter, don't assume it's an oversight.
For informal picnics or last minute get togethers where no invitations are actually sent, the rules are totally different and very much more relaxed. Let common sense be your guide. When it's your turn to throw the bash, you'll appreciate the cooperation from your guests as well.