My family moved from the suburbs to the country when I was five. Not only did I insist that we pack a box for my imaginary friend's stuff, but I made my mom promise that there would be room for her in our new house. When we moved, however, Mom -- trying to get me to grow up -- told me that my imaginary friend found a new family to live with and wouldn't be coming with us. I cried for weeks and tried to walk the 20 miles back to our old house to find her.
But it's ok. 29 years later, I've almost stopped being angry about it.
A childhood belief about imaginary friends

others believed things like this
- when i was younger i thought that when you moved house your house moved with you!!— chrissy
- I used to have an imaginary friend named Mr. Nobody. He would protect me from my imaginary enemy, Bad Elmer.— Kdees
- I used to believe that when you moved house you swapped house with the person moving into your old house.Anon
- when i was young i believed that when u moved house the house would come with you !!!
just like a turtleAnon - I used to think when we moved, it was because we were exchanging our house with the buyer's... — Pat
- I used to belive that when you moved, a big crane picked up your house and dropped it somewhere else.Anon