After nine years of dating, Holly is sure her boyfriend Will is going to propose. But instead of popping the question, he shocks her by suggesting they open their relationship to date other people. For the last three years, Fliss and her boyfriend Ash have been in a happily open relationship. But now that they’re turning thirty, he wants to close it, throwing Fliss’s whole ethos of living life on her terms rather than society’s expectations into question. When Fliss overhears Holly crying in the toilets during her first date in nine years, they decide to ditch their dates and have dinner together. They strike up an instant friendship with Fliss agreeing 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. Fliss is willing to give up dating other people if it means staying with Ash, and Holly is willing to try anything if it means she gets her happy ending with Will. But perhaps both Fliss and Holly will learn that there’s no one size fits all when it comes to relationships . . .