User blog comment:B214/Question and Answers 2/@comment-4547267-20140227025003/@comment-1359322-20140227032446

Harem and Peerage are different. Issei already has a harem with all the girls around him. His peerage is something he'll use to help him in battle when needed and to fight in Rating Games. In conclusion, a Peerage doesn't have to be a harem, they are two very different things.