Trailer disconnects when i get into vehicle, then when i get out, trailer slowly slides across the ground and reconnects

As the title states I’m having a very strange issue where when I hookup a trailer to my truck it will hookup how it normally does then it will just “pop” off and fall to the ground. If I drive forward a bit, stop and get out of the vehicle the trailer will slowly slide across the ground and eventually make it to the truck and rehook. Any help/input would be greatly appreciated!