I'm getting married this fall, and we've done our best to keep the guestlist under 100 people. Of course a smaller guestlist has meant making a lot of tough decisions about who not to invite, but them's the breaks.
…Except for now I just got an invitation to an acquaintance inviting me to HER wedding! Needless to say, this is an acquaintance who I'm NOT inviting to our wedding. I feel bad — if I say yes to her invitation, do I owe her an invitation to our wedding? If I say no because I can't afford to invite her to our wedding, am I basically punishing her twice?
UG. Of course wedding planning is fraught with all sorts of challenges, but guestlist drama is definitely top of the list when it comes to producing mad amounts of social anxiety.
Let's start with the opinion of the Official Guardians of Tasteful Wedding Etiquette (aka random people posting on mainstream wedding forums):
Etiquette says, that any time you are invited to a social event involving a meal or some significant entertainment, you have two obligations. You must send a thank-you note to your hostess within a day or two. And, you must return the invitation with an invitation to an event of similar significance, sometime within the same season.
So, unless you are getting married in the same season as everyone else you know, the return obligation isn't likely to be a wedding. "Similar significance" means a dinner invitation in return for a dinner invitation; a theatre or concert party in return for a theatre party; an afternoon coffee in return for afternoon coffee. This social debt expires at the end of the season: so, even if you didn't know that you were supposed to have the new couple over for dinner some time in the weeks following their honeymoon, you're still in the clear for all but the most recent weddings.
Similar significance! Social debts! Return obligations! Who knew this would start to feel so… transactional. That said, the Official Guardians of Tasteful Wedding Etiquette aren't totally wrong: there are a lot of complex factors that come into making a decision like this, and none of them are easy.
The first thing to consider is your future relationship with this person. You say she's an acquaintance, which implies that she's not a close friend. Regardless of what title you'd give this person, think about whether you'd like to keep in touch with her in the future. Is this a relationship you'd like to continue? Then it might be worth trying to create the space in your guestlist, in the interest of that future relationship.
If, however, she's truly an acquaintance who you don't have a strong connection with, then there's no need to invite her. I'd suggest declining the invitation to her wedding, but sending a lovely gift so as not to feel like you're "punishing" anyone. This is more than just about tit-for-tat: do you want to attend the wedding of a person who you're not that close to? If you're not inviting her to your wedding, is she a close enough friend to attend her wedding?
Alternately, you could consider going with the whole "transactional" approach, declining your acquaintance's invitation, but invite them out for a nice dinner after the weddings are done, as a way to celebrate y'all's new married life. (Trust: parties and entertaining shouldn't stop with your wedding! Married people need to keep having more parties!)
Keep in mind also that people have vastly different weddings, with vastly different budgets and family situations. Your acquaintance may be having a large, family-funded wedding while you're budgeting out of your own pocket. We all know this: engaged couples have all sorts of different priorities, all sorts of different budgets, all sorts of different reasons for inviting guests. All weddings are not created equal, and this is not necessarily a game of wedding tit for wedding tat. That said, there's no guarantee that feelings won't be hurt. The best you can do is go into the decision with your eyes open to that fact, and a sense of loving open-heartedness toward your fellow bride.
In summary? Don't feel like you have to invite anyone, but don't expect to not feel bad about the decision.
Would you feel obligated to invite someone to your wedding if they invited you to theirs? How long do the social debts last? Can you repay a wedding debt with a pound of flesh?