Danny was engaged to Bonnie Crasnoff until her death.
His fiancée, Bonnie, was in a train crashed. She was impaled through the chest and connected to another man. They were examined and the doctors determined they'd have to take Bonnie off the pole in order to give Tom Maynard a chance at life. Shortly after they removed Bonnie from the pole, she was pronounced dead. She left a message for Danny with Derek Shepherd, saying that if love were enough, she'd still be there.
He was engaged to Bonnie Crasnoff until her death.