We had our wedding earlier last month! It was fantanstic. To make a long story short, my DH has this weird relationship with his mom's side of the family. His cousin and his date accepted the wedding invitation, showed up, but then left after our bridal party (and us) made our entrance.
I found it quite odd. They pretty much came up to us and said "we're leaving now." something along those lines, i cant remember but i do know that they didn't give us a reason why they were leaving..no they hadnt gotten to a fight/disagreement at the wedding so that wasnt the reason
I found it quite rude! Had we known that they were only going to come to the ceremony and leave the reception we wouldn't have paid for their plates. Given this "odd relationship" with his family, I think they had planned all along to leave early. Why do this? People suck. lol