If the guardian himself is the suitor
حَدَّثَنَا ابْنُ سَلاَمٍ، أَخْبَرَنَا أَبُو مُعَاوِيَةَ، حَدَّثَنَا هِشَامٌ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ فِي قَوْلِهِ {وَيَسْتَفْتُونَكَ فِي النِّسَاءِ قُلِ اللَّهُ يُفْتِيكُمْ فِيهِنَّ} إِلَى آخِرِ الآيَةِ، قَالَتْ هِيَ الْيَتِيمَةُ تَكُونُ فِي حَجْرِ الرَّجُلِ، قَدْ شَرِكَتْهُ فِي مَالِهِ، فَيَرْغَبُ عَنْهَا أَنْ يَتَزَوَّجَهَا، وَيَكْرَهُ أَنْ يُزَوِّجَهَا غَيْرَهُ، فَيَدْخُلَ عَلَيْهِ فِي مَالِهِ، فَيَحْبِسُهَا، فَنَهَاهُمُ اللَّهُ عَنْ ذَلِكَ.
Narrated `Aisha: (regarding His Statement): 'They ask your instruction concerning the women. Say: Allah instructs you about them ...' (4.127) It is about the female orphan who is under the guardianship of a man with whom she shares her property and he does not want to marry her and dislikes that someone else should marry her, lest he should share the property with him, so he prevents her from marrying. So Allah forbade such a guardian to do so (i.e. to prevent her from marrying).