We Got Us a Pippi Virgin - S5-E5
Continuity mistake: When they are starting Pippi and Luke is asking about her hair, you can see Dean's hand on Rory's shoulder on the side of the shot. Then it pans to them and then Dean is putting his arm around Rory.
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.