Corruption would bring me down but I might manage to start over again at some point.
Boredom is the number one cause of my long Animal Crossing hiatuses. This is the second time I've basically forgotten about the game and only started playing again after months and months have passed. At some point, likely after I've finished my town and played through the remainder of the year, I'll have seen most (if not everything) in the game. (All festivals, everything catalogued and in the museum, etc.) That's usually the point when I stop playing a game, even if it can essentially keep going on forever.
...except if I get a second copy, of course. Then maybe it can start all over again...