He met Carole while working with him on the Omega 7 mining colony. She was transferred back to Earth, and when the Drakh attacked and she was unable to leave the planet because of the quarantine. David called her from the Excalibur to tell her that he was coming home. This was something she objected to but accepted.
To return home, he elected to be infected with the Drakh plague, and have the virus be tracked through his system from the moment it entered his body. Stephen Franklin was brought on board the ship and performed the test.
Because he had broken the communications silence and contacted his wife, the Drakh attacked the Excalibur, which jeopardized David's life when his isolation room seals were breached. This set off an auto-decontamination procedure that would sterilize anything in the room. Because he was knocked unconscious, Franklin had to quickly get into the room and rescue him. David was saved with moments to spare.
Franklin was invited to the wedding, in part for saving his life, and reuniting him with his love. David and Carole were married a week after they talked.