Three's Company (1977)

Season 3: Episode 8

Larry introduces the trio to his new fiance. Jack learns that Gloria has always had the hots for him, but Larry believes it to be the other way around. Jack unsuccessfully tries to talk Larry out of marriage. Chrissy unknowingly stumbles upon the real reason Gloria is marrying Larry, because he told her he owned a used car lot. Larry figures out what Jack was trying to tell him, and Gloria learns the truth about Larry. The conclusion is something both Gloria & Larry agree on!