Hmm I don't really agree with any of the replies to my comment. The person doesn't have enough space/resources to invite everyone she wants to invite +1. Why is that difficult to comprehend? I couldn't have a dinner for more than a few people, and it would be more important me to have all my there than to have half my friends and half a bunch of people I don't really know who aren't really part of the particular crowd that the party is aimed at.

None of it has to do with couples ditching single friends or any of the like. The LW has not mentioned that any of the couples have done so. My issue is with the idea that it is incomprehensible for a person in a couple to be invited somewhere on their own. Couples do not always share the same friends, they don't always share the same interests. Furthermore, if, at any event, someone is automatically assumed to bring a "plus 1" that should go for everyone, and the plus one should be allowed to be anyone, not just a romantic partner.

For some occasions the LW might be hosting, plus ones may be welcome. However, it is clear from the letter that she simply cannot accomodate them at this particular event, and that it's not really necessary for them to be there anyway. Why it's wrong not to invite them, I do not know.

For anyone who suggested that "singlism" (not my term) does not exist or that I have a "chip" on my shoulder, wake up. Sure this is one little dinner party at someone's house, but the "etiquette" rules Prudie has applied are part of a broader cultural problem. Our entire society- including little etiquette rules- is based on coupling, and there's no grounds for that anymore. The whole situation just says a lot about what's going on out there.