Blair is a huge fan of Bones and listens to the radio show. When they were in Nashville, they stopped by the studio during the evening. Due to some construction going on around the building, the parking garage was open. They decided to walk in the garage and found Bones parking spot complete with his sign hanging up. Her boyfriend Josh decided to pop the question at the very special spot. He got down on one knee in Bones parking spot and asked Blair to marry him. She said yes and they spent the rest of their time in Nashville celebrating.
They are looking for the security camera footage from the garage of the proposal, but Bones noted with all of the construction going on they likely weren't up at the time.
Everyone from the show wishes the happy couple a big congratulations!