Is there any guide? I never flirted with Cove, did every Moment during each Step, did any choice to flirt with Derek and even took him to the dance, and Step 4 never gave me the option to pick Derek.
Did you choose to keep in touch with him while you were apart during Step 3? And did you do the Moments on the second page? There's a button on the right side of the Step 2 Moment select screen that lets you switch to five Derek Moments.
