I think the saddest moment for me was when I lost Stitches because he moved out without my permission. When I was determined to do the 16-villager cycle just for him, another one of my Dreamies, Lolly, also left. At that point, I gave up and restarted a new town. (Yes, I got too affected I-) In the end though, that moment happened 3 years ago, and now I'm in my best town.