When getting a wedding invitation isn't a good thing:
You thought you would be in the wedding party. You guys are great friends. She would be one of your bridesmaids. And now, here you are, reading your mail in the street and completely offended. This doesn't mean you aren't friends. There are times when selecting a wedding party looks more like brokering a Middle East peace agreement than picking out your best friends. Lots of people (those pesky family members) need to be considered. Whatever you do, don't confront the bride or ask her why. That will just make you look bad. If this is a dealbreaker for you, that's your choice. Otherwise, go and have a good time.
You can't afford it. Whether it is a destination wedding and you don't have the miles, or a black tie affair and you don't have the dress, sometimes finances get in the way. You don't need to make a big deal out of it, or feel embarrassed. Decline the invitation, send a sweet card and whatever gift you can afford, and call it a day. If the bride calls you disappointed, tell her the truth: it's not in the budget right now, but you can't wait to see the pictures!
You receive two wedding invitations for the same day. Especially if the brides know each other, this is an "uh-oh" situation through and through. But the solution is simple enough: go to the one you want, but make sure to send a gift to the other.
You used to date the groom. You get an invitation from your college roommate and (even though you've lost touch) are thrilled, until you look at the groom's name. After you graduated, you dated him for a year. Yikes! Especially if you get the feeling that the bride doesn't know (grooms rarely give the guest list the fine tooth comb treatment), just don't go. So awkward.
Photo Credit: jHenderson Studios