User blog comment:TheBlueSlug/Who should issei end up with?/@comment-4823600-20131113224236/@comment-1359322-20131114015132

Like Dante said, Devils are known to have low birth rate, Issei himself is a Devil too, while i won't deny the chances his Dragon side might increase his fertility but that won't work for the girls. Also since Rias and Akeno are constantly scattering his Dragon powers so i doubt he has enough to use leisurely anyways.