@kuzunagi13: I know this is an old thread to respond to, butttt although masturbation is not counted directly addressed as either good or ill in the Old Testament Bible,
lust is counted among the original Seven Deadly Sins; and therefore the idea that angel, who is supposed to be 😇an embodiment of goodness and purity😇, is lusting after this human girl and likely having perverted fantasies must have been the reason for the angel's fall from grace, so to speak lol.
Personally, I think the (fallen)angel and demon girls would make a nice couple.