Why can’t the Fifty Shades franchise drag on indefinitely like everything else?

The final installment in the Fifty Shades trilogy, Fifty Shades Freed, arrives in theaters this weekend. It’s a movie about marriage, boobs, exorbitant wealth, getting bullied by poor people, and above all, the ins and outs of the independent publishing industry. It’s the final chapter in the trilogy of adaptations of E.L. James’ Fifty Shades of Grey books: 2015’s Fifty Shades of Grey, which only an alien could love, and 2017’s Fifty Shades Darker, which we mathema