Joseph was far from his family in a land where nobody knew him. He may well have been able to have relations with this woman without other people being aware of it.
وَبِمَا أَنَّ يُوسُفَ كَانَ بَعِيدًا عَنْ عَائِلَتِهِ فِي بَلَدٍ لَا يَعْرِفُهُ فِيهِ أَحَدٌ ،‏ كَانَ بِإِمْكَانِهِ أَنْ يُمَارِسَ مَعَهَا ٱلْعَلَاقَاتِ ٱلْجِنْسِيَّةَ دُونَ أَنْ يَدْرِيَ أَحَدٌ .‏