As Radha was the aunt of Krishna, isn’t their relationship illicit?

ISKCON forbids illicit relationship/sex. Radha was Krishna’s maternal aunt ( ie: Mami ). Is this not illicit relationship? And he had sexual relationship with her. Krishna is married to Rukmani the daughter of King Rukmangad. Radha was married to Krishnas uncle. Krishna who abandons his lawfully wedded wife Rukmini and seduces Radha wife of another man and lives with her in sin without remorse. Here you cannot say just because Krishna is the supreme being he is justified doing this. In-fact if he is so all knowing he could have made Radha like maybe sister of Krishnas uncles wife atleast he would have been saved the blasphemous act of having sex with her maternal aunt.