The genesis of this film was generated from a night out in Paris, France where the film's two directors, Marisa Silver and Ken Kwapis, were both telling the story of how the pair had gotten together. They noticed that their stories were different in perspective, so they decided to make a movie based on this high concept, and shortly afterwards, contacted the film's Screenwriter Brian Hohlfeld to develop the movie, then pitched the picture to Paramount, who gave them the go-ahead.
This was not the first movie about relationships to split the film into two main segments, titling them with gender-specific terms, each telling a story from each gender's perspective. The Richard Burton-Elizabeth Taylor television movie Divorce His - Divorce Hers (1973) had done this.
Ken Kwapis and Marisa Silver, who filmed "He Said", and "She Said", respectively, each watched each other's segments being filmed, so they would be cogniscent of how to vary each's own segments from the other. However, each when watching the other's segment being shot, were not allowed to talk to the actors during it.
The framing story which has Lorie (Elizabeth Perkins) throw a coffee cup at Dan (Kevin Bacon) functions to differentiate the "present" time-frame of the picture from the "past" time-frame as it results in him having a sore requiring a bandage, thereby acting as a visual signifier to the audience that whenever he appears with this, that it is the present and not the past.
Ken Kwapis and Marisa Silver are married, but weren't at the time the movie was made. They were then, like the film's two lead characters, boyfriend and girlfriend. According to Variety, the two got engaged during the film's production.