A: Nope. You're expected to invite the spouses, fiancé, live-in partners and serious beaus of your guests, but anyone less committed can fly solo. Just make sure that what you think of as "less committed" mirrors the sentiment of the guest that falls into that gray area, to avoid offending someone who's fallen head-over-heels in the last three weeks. Ask a trusted friend if you aren't positive about someone's dating status. Rest assured that at least one or two of your single pals will call and ask about bringing a tag-along. If they do, tell them that you simply can't accommodate any extra guests. If they refuse to come without a date, then so be it. Invite someone else who might turn out to be a better friend in the long run.