[freakshow]

I've seen this happen many times, and I've both received and issued invitations that are 'ceremony only'.

The couple is inviting you to a very special day in their lives, and they have reasons, be it budget, or otherwise, that they can't invite everybody to the reception.

You can respond in one of two ways:
1. Be humble and thankful that you were invited to share with them, go enjoy the ceremony, and wish them the best.

or 2. Be a self-entitled princess, pouting about what you think you deserve. Whether you go or not makes no difference, because it's your attitude that needs a check. If this is your attitude, you're obviously not a good friend, and probably shouldn't have even been invited to the ceremony. I know that if it was my wedding, and that's how you felt, I would rather have you not come anyways.