According to The Muppets Character Encyclopedia, all of Kermit and Piggy's weddings have been fictional, but Piggy carries around a marriage license in her purse, just in case. “In the show's course there's a wedding, led by a little, old man who acts as minister... As the film ends, it's apparent that Kermit has married Miss Piggy. Kermit says - and will continue to say - on interviews and such, "I'm just an actor and when two actors marry on stage, they're only acting." But Miss Piggy continues to bring in this minister as evidence that they're really married. So, the argument will continue on hopefully into — I don't know what — we'll wait and see.— Jim Henson, August 1984”