User blog comment:B214/Volume 23 discussion blog/@comment-31137559-20170326233819/@comment-31137559-20170327025114

Not really. We have to consider that this is the devils' society, not the human society where you can only have one woman at a time. Their views on that differ from ours. That's like saying that Issei only having Rias and ignoring the others' feelings is the right thing to do.

By our real world society's standards, having one woman at a time and being faithful to her is the right thing to do. That's assuming that a man can only love one woman romantically at a time. He can't love more than one woman and share love with all of them romantically.

Venelana was the daughter of her father's second mistress. Lord Bael had two wives(I speculate that he was married to both of them at the same time. They were able to both be married to him because they were both pureblood high-class devils. And he was the head of the most powerful house in the Underworld). Lord Gremory and Riser have a harem. Issei has a harem. If it was something so unusual, then the high-class devils would voice their dissent.