It means that they see and know each other, but for being occupied with themselves they do not ask about each other because they find this pointless. The unjust transgressing sinner who went beyond the limits, disbelieved in Allah (swt) and was too proud to worship Him (swt):

(  يَوَدُّ الْمُجْرِمُ لَوْ يَفْتَدِي مِنْ عَذَابِ يَوْمِئِذٍ بِبَنِيهِ… ) (…The criminal will wish that he could be ransomed from the punishment of that Day by his children): As they were guilty, they want to be delivered from Allah’s punishment inflicted on them, to the extent that they wish to be ransomed by their own children, whom they invoked Allah (swt) to give in the worldly life, or by their spouse who shared their lives and even by their brother, family, relatives, kin and whoever is on earth entirely. The are willing to sacrifice everyone else so that they could redeem themselves from the Allah’s punishment. However, Allah (swt) shatters the hope of the disbelievers, oppressors and the guilty regarding escaping His punishment. In this regard, Allah (swt) says:

 إِنَّ الَّذِينَ كَفَرُوا وَمَاتُوا وَهُمْ كُفَّارٌ فَلَن يُقْبَلَ مِنْ أَحَدِهِم مِّلْءُ الْأَرْضِ ذَهَبًا وَلَوِ افْتَدَىٰ بِهِ ۗ أُولَٰئِكَ لَهُمْ عَذَابٌ أَلِيمٌ وَمَا لَهُم مِّن نَّاصِرِينَ

(Indeed, those who disbelieve and die while they are disbelievers – never would the [whole] capacity of the earth in gold be accepted from one of them if he would [seek to] ransom himself with it. For those there will be a painful punishment, and they will have no helpers.) (Ali-Imran: 91)