You can use the Dizzy's Delightful Doughnuts feeder upgrade to raise the town's obesity rate. Once it's at 99%, you can move to a new town. Each time you do so, the UK obesity rate will rise, making each new town fatter than the last (amongst other effects).
Your fiancée should move with you, but the other girls will all remain in the old town.
You can travel back at any time, but your partner won't return with you, she'll only follow you to new towns. That's something I'm looking to change very soon.
