User blog comment:TheBlueSlug/Ending/@comment-213.120.234.122-20141115123857/@comment-24098614-20141115230654

I hope you read the High School Dxd story from the beginning Issei is not your average person, and you have heard what he dreams about he doesn't want a Monogamy but a Polygamy blame the old man in the series for making him into a pervert because this gives Issei his charm.

Rias already tried in her own way to keep him by herself but it has failed because Issei doesn't want just Rias because he is like a typical Devil that is driven by desire and doesn't settle for just one, and the girls all love him and Issei doesn't have the heart right now to tell them to scram out of his life because he is a pervert but he has a big heart.

I can tell you if you want a single pairing look for another series because it is sure not happening in Dxd because Issei wants his Oppai and his Harem blame him for what he is.