User blog comment:B214/Question and Answers 2/@comment-24098614-20140321234015/@comment-9339850-20140321234518

Its a complicated situation since she, Issei and Michael all want her to stay as an angel; thats why they are doing so much research. And it would open up for all kinds of relationships to happen. The only reason Fallen Angel/Devil relationships are publicly accepted is because of the Three Faction's treaty. If Angels were allowed to freely be in relationships without Falling, then it'd strengthen relations between the factions even more.