The Love Boat (1977)

Season 3: Episode 15

Gopher finds romance with a recently separated passenger--until her estranged husband suddenly shows up and announces his intention of winning her back. A woman tries to pry her soon-to-be-ex-husband away from his girlfriend by coming on the cruise and rooming in the cabin next to theirs. Two distinguished passengers, who squared off in a boxing match decades earlier, renew their rivalry. They schedule a fight on the ship to settle the score once and for all.