This is just something I was curious about - if you are inviting a friend who has a significant other that they're not living with, do you send an invitation to each of them, or just to the friend with both names on the invite?
For example, let's say you're friends with John X, and he is dating but not living with Jane Y. You've met Jane Y a couple of times but don't know her at all outside her relationship with John X. Do you send Jane Y her own invitation, or do you just send one invite to John X's address with both their names on it?
When the time comes to send out invitations, I'll do whatever's considered most polite, but I just think it would be kind of strange to send a separate invitation to someone that you have only met a couple of times who might not remember who you are. But let me know what you guys think.