His usual scenario is to read a girl mind, adapt his behavior to her preferences, and tell her what she wants to hear. He targets mostly girls with lack of self-confidence. He makes them believe that only him truly love them, and once he got tired of them. He dumps them, either the princess "take care of them" by jealousy, sells them to slavery, or he makes them do some dirty work to gain some time with him. At this level, these girls are usually abandoned by their family with nowhere to go and cling to him for affection.
He keeps the princess because she is his ticket to the throne, and that it. The princess is fully aware of him ruining others people's lives and sides business, but blame the others girls to exists instead of him.