SPOILER ALERT: This story contains spoilers from “Fair Play,” now streaming on Netflix. When Phoebe Dynevor read the first pages of the script for “Fair Play,” a relationship thriller set in the cutthroat world of hedge funds, she thought, “Fuck yeah.” The opening moments of the film, from writer-director Chloe Domont, are focused on Emily and Luke, a young couple who sneak away from his brother’s wedding reception for a quickie in the bathroom, only to discover that she’s gotten her period. Now there’s blood on his face and all over her dress.