User blog comment:TheBlueSlug/Who should issei end up with?/@comment-24.135.60.109-20140818084729/@comment-23853100-20140818141744

^^This. Issei wishes to have a harem (even though he doesn't know he has one already). Plus if Issei is placed in a situation where he has to choose between Rias or his friends, Issei would probably put his all into protecting both side even if he has to sacrifice his own life to save both side.