However, a behind-the-scenes video has now revealed that a perspex screen was used to help create the scene, while Marcel's real-life husband, Ben Stacey, was called in to film the actual kiss.
"We needed to do a kiss and it's very difficult with the perspex and things like that," she said in the video.
"So my lovely husband came in to do a little kiss with me, which is really nice, and really weird."
Rosie with husband Ben Stacey
David M. Benett/Getty Images
Explaining how filming with a perspex screen between them worked, Kian actor Ramin Karimloo said: "Most of the scene was done with perspex between myself and Rosie.