The creators of Friends originally intended Monica and Chandler's hookup to be a one-time surprise rather than the start of a serious relationship. A strong audience reaction during filming changed their minds. The pair first connected in the Season 4 finale.
Co-creator Marta Kauffman said the studio audience applauded the reveal for two minutes when the characters slept together during Ross's wedding in London.
"We kind of went, 'Huh, this is such an unexpected duo, let's play with it for a little while,'" Kauffman told Entertainment Weekly.
The creators had not expected the pairing to grow into one of the show's central storylines alongside Ross and Rachel. "Our intention was not for them to be as serious as they became," Kauffman added.
After keeping the relationship secret at first, Monica and Chandler married within three seasons, turning the unplanned twist into one of the longest-running romances on the series.