Δαφνη Ευτυχια Αρθουρος

Weddings are typically invite-only, yes: although there's a tradition that if people get married in a church, any member of the church can attend the wedding (but not reception, unless invited). But there's quite a bit of "look, we're getting married" that isn't in private or invite-only: wedding photographs are often taken in public parks, with the people being photographed in standardized wedding clothes. Wedding planning often becomes a major topic of conversation, even with people who aren't invited (and might not care to be), notably co-workers who find themselves overhearing lengthy conversations about catering, flowers, et cetera. It's also a lot bigger deal, socially and emotionally, to say "No thanks, I don't want to go to your wedding" than to decline most other invitations.

I'm only aware of one case of people who invited their friends to a social event and then revealed, after everyone had arrived, that it was their wedding. As far as I know, everyone there thought it was cool: after all, they liked their host enough to have accepted her invitation to a party. But if they hadn't, it would have been a lot harder to walk out than it would be to decline an invitation, claiming other commitments. (I think the reason for surprising the guests was so that they wouldn't feel the need to buy gifts.)