in the Lady attire, find an NPC with an empty heart floating above his head. Get near and hit Circle to fill it up (with love, presumably). He'll follow you. Now, look around for another NPC with an empty heart. As you go, your follower's icon will start to drain, but you can press Circle again to keep him interested. Once you find a second guy, charm him with Circle, thereby cancelling the charm on the first guy. Simply charm the first guy again, then the second again, back and forth, until you get the trophy.
As with most of these "do something X number of times" challenges, progress does NOT save if you die or quit. So either get this in one session, or make sure you do something (such as starting a new mission) to make the game save your progress.