The Incredible Sinking Lorelais - S4-E14
Continuity mistake: Dean calls Rory, and towards the end of the conversation mentions getting his first cell phone. This is false. He's had a cell phone the whole series. Paris even calls it in the season 2 episode "Can't Get Started" when Rory and Dean are at Sookie's wedding.
Chosen answer: Lorelai and Christopher get married impulsively in Paris but they get divorced shortly after returning home. I don't know the exact number of days or weeks but they definitely weren't married for more than a couple of months.