Rosie the robot's boyfriend in The Jetsons is Mac, also identified as M.A.C.C.
Mac appears as a robotic assistant working for Henry Orbit, the superintendent of the Skypad Apartments. Their relationship is introduced in the episode “Rosey's Boyfriend,” in which Rosie develops feelings for him. Mac is portrayed as less sophisticated and more childish than Rosie, who is generally the more capable and intelligent robot.
Rosie herself is the Jetson family's robotic maid and housekeeper. She is an older demonstrator model, identified in the series as model XB-500, and her outdated status is a recurring source of stories. Her name is sometimes spelled “Rosey” on episode title cards, which explains a common variation in references.
Mac is easy to confuse with other Jetsons robots, especially R.U.D.I. and Uniblab. Those characters are separate machines with different roles. Mac's romance with Rosie is a small but memorable subplot in the show's broader cast of futuristic robots.