The course of true love never did run smooth, especially when your soulmate is a 900 year old alien who has been making sporadic reappearances since you were a child! As far as the Tenth Doctor was concerned, his encounters with Madame de Pompadour in Series 2 took place over the course of a day but he managed to imprint himself on her entire world when the Clockwork Droids opened gateways during her formative years and beyond. Stuck on the slow path, Reinette eventually passed away but left the Doctor with a heartbreaking letter in which she affirmed the significance he'd had on her otherwise lonely life. Time travel had never been so cruel. Rather unsurprisingly, it was a Steven Moffat script.