Mathias and Alexia have been a couple for years, but he is now cheating on her for the first time, with Juliette, a wedding planner... When Alexia finds Juliette's business card in Mathias' pocket, he loses his footing, he stammers... She understands immediately: Juliette is a wedding planner, so that means that he must want to marry Juliette! She says "YES". Mathias unwittingly finds himself torn between his 'wife' and his 'mistress', and forced to organize an unplanned wedding!