What if The One isn't the only one?
After nine years of dating, it's a question of when not if Holly's boyfriend Will is going to propose. She's blindsided when rather than popping the question, he suggests they open their relationship and date other people.
For the last five years, Fliss and her boyfriend Ash have been in a happily open relationship, but, now they're turning thirty, he wants to close it which throws Fliss's whole ethos of living life on her own terms rather than society's expectations into question.
Fliss isn't sure she's ready to give up on dating other people yet, and Holly is willing to try anything if it means she gets her happy ending with Will. Fliss agrees to teach Holly everything she knows about being in an open relationship while Holly who's been with one person for almost a decade can help Fliss try monogamy. But perhaps both Fliss and Holly will learn that there's no one size fits all when it comes to relationships…