Heart Broken

My son moved out.  Not actually out of the house, he's only 3.  He moved out of my bed. Completely out of the blue he went to sleep in his own bed.  At first I thought it was just a cruel April fools day joke but when he went into his own bed the second and third night I knew it wasn't a joke.  Even when I sublimely suggested that he might like to to sleep in my bed he still chose his own. My heart is broken ( just a little) and now something isn't right when I go to bed at night.  It's just not the same.  The balance has been shifted and I don't like it.  What am I going to do when he goes to school?